It is estimated that the Second World War was responsible for the deaths of approximately 3.76 percent of the world's population between 1939 and 1945. In 2022, where the world's population reached eight billion, this would be equal to the death of around 300 million people.

The region that experienced the largest loss of life relative to its population was the South Seas Mandate - these were former-German territories given to the Empire of Japan through the Treaty of Versailles following WWI, and they make up much of the present-day countries of the Marshall Islands, Micronesia, the Northern Mariana Islands (U.S. territory), and Palau. Due to the location and strategic importance of these islands, they were used by the Japanese as launching pads for their attacks on Pearl Harbor and in the South Pacific, while they were also taken as part of the Allies' island-hopping strategy in their counteroffensive against Japan. This came at a heavy cost for the local populations, a large share of whom were Japanese settlers who had moved there in the 1920s and 1930s. Exact figures for both pre-war populations and wartime losses fluctuate by source, however civilian losses in these islands were extremely high as the Japanese defenses resorted to more extreme measures in the war's final phase.

Estimates for the total death count of the Second World War generally range somewhere between 70 and 85 million people. The Soviet Union suffered the highest number of fatalities of any single nation, with estimates mostly falling between 22 and 27 million deaths. China then suffered the second greatest, at around 20 million, although these figures are less certain and often overlap with the Chinese Civil War. Over 80 percent of all deaths were of those from Allied countries, and the majority of these were civilians. In contrast, 15 to 20 percent were among the Axis powers, and the majority of these were military deaths, as shown in the death ratios of Germany and Japan. Civilian deaths and atrocities It is believed that 60 to 67 percent of all deaths were civilian fatalities, largely resulting from war-related famine or disease, and war crimes or atrocities. Systematic genocide, extermination campaigns, and forced labor, particularly by the Germans, Japanese, and Soviets, led to the deaths of millions. In this regard, Nazi activities alone resulted in 17 million deaths, including six million Jews in what is now known as The Holocaust. Not only was the scale of the conflict larger than any that had come before, but the nature of and reasoning behind this loss make the Second World War stand out as one of the most devastating and cruelest conflicts in history. Problems with these statistics Although the war is considered by many to be the defining event of the 20th century, exact figures for death tolls have proven impossible to determine, for a variety of reasons. Countries such as the U.S. have fairly consistent estimates due to preserved military records and comparatively few civilian casualties, although figures still vary by source. For most of Europe, records are less accurate. Border fluctuations and the upheaval of the interwar period mean that pre-war records were already poor or non-existent for many regions. The rapid and chaotic nature of the war then meant that deaths could not be accurately recorded at the time, and mass displacement or forced relocation resulted in the deaths of many civilians outside of their homeland, which makes country-specific figures more difficult to find. Early estimates of the war’s fatalities were also taken at face value and formed the basis of many historical works; these were often very inaccurate, but the validity of the source means that the figures continue to be cited today, despite contrary evidence.

In comparison to Europe, estimate ranges are often greater across Asia, where populations were larger but pre-war data was in short supply. Many of the Asian countries with high death tolls were European colonies, and the actions of authorities in the metropoles, such as the diversion of resources from Asia to Europe, led to millions of deaths through famine and disease. Additionally, over one million African soldiers were drafted into Europe’s armies during the war, yet individual statistics are unavailable for most of these colonies or successor states (notably Algeria and Libya). Thousands of Asian and African military deaths went unrecorded or are included with European or Japanese figures, and there are no reliable figures for deaths of millions from countries across North Africa or East Asia. Additionally, many concentration camp records were destroyed, and such records in Africa and Asia were even sparser than in Europe. While the Second World War is one of the most studied academic topics of the past century, it is unlikely that we will ever have a clear number for the lives lost in the conflict.

The 20th century marked a new trend in the recording of war fatalities, where more attention was given to the impact of conflicts on civilian populations, and not just the military. During the Second World War, the extent of the atrocities committed, the large-scale bombing campaigns, and the various famines resulting from the war meant that the scope of the civilian death toll took place was unprecedented - the likes of which had never been seen before, or since. Almost two thirds of all deaths due to the Second World War were of civilians, yet the ratio of military to civilian deaths varied greatly by country. Many British dominions and the United States suffered little to no civilian deaths as they were not located in an active theater of war - civilian fatalities largely came from naval or aerial attacks (such as at Pearl Harbor). In contrast, there were several European colonies in the Asia-Pacific region where all, or at least 95 percent, of total fatalities were among civilians - some of these regions suffered millions of deaths due to famine and atrocities.

The First World War saw the mobilization of more than 65 million soldiers, and the deaths of almost 15 million soldiers and civilians combined. Approximately 8.8 million of these deaths were of military personnel, while six million civilians died as a direct result of the war; mostly through hunger, disease and genocide. The German army suffered the highest number of military losses, totaling at more than two million men. Turkey had the highest civilian death count, largely due to the mass extermination of Armenians, as well as Greeks and Assyrians. Varying estimates suggest that Russia may have suffered the highest number of military and total fatalities in the First World War. However, this is complicated by the subsequent Russian Civil War and Russia's total specific to the First World War remains unclear to this day.

Proportional deaths In 1914, Central and Eastern Europe was largely divided between the empires of Austria-Hungary, Germany and Russia, while the smaller Balkan states had only emerged in prior decades with the decline of the Ottoman Empire. For these reasons, the major powers in the east were able to mobilize millions of men from across their territories, as Britain and France did with their own overseas colonies, and were able to utilize their superior manpower to rotate and replace soldiers, whereas smaller nations did not have this luxury. For example, total military losses for Romania and Serbia are around 12 percent of Germany's total military losses; however, as a share of their total mobilized forces these countries lost roughly 33 percent of their armies, compared to Germany's 15 percent mortality rate. The average mortality rate of all deployed soldiers in the war was around 14 percent.

Unclarity in the totals Despite ending over a century ago, the total number of deaths resulting from the First World War remains unclear. The impact of the Influenza pandemic of 1918, as well as various classifications of when or why fatalities occurred, has resulted in varying totals with differences ranging in the millions. Parallel conflicts, particularly the Russian Civil War, have also made it extremely difficult to define which conflicts the fatalities should be attributed to. Since 2012, the totals given by Hirschfeld et al in Brill's Encyclopedia of the First World War have been viewed by many in the historical community as the most reliable figures on the subject.

In 1938, the year before the outbreak of the Second world War, the countries with the largest populations were China, the Soviet Union, and the United States, although the United Kingdom had the largest overall population when it's colonies, dominions, and metropole are combined. Alongside France, these were the five Allied "Great Powers" that emerged victorious from the Second World War. The Axis Powers in the war were led by Germany and Japan in their respective theaters, and their smaller populations were decisive factors in their defeat. Manpower as a resource In the context of the Second World War, a country or territory's population played a vital role in its ability to wage war on such a large scale. Not only were armies able to call upon their people to fight in the war and replenish their forces, but war economies were also dependent on their workforce being able to meet the agricultural, manufacturing, and logistical demands of the war. For the Axis powers, invasions and the annexation of territories were often motivated by the fact that it granted access to valuable resources that would further their own war effort - millions of people living in occupied territories were then forced to gather these resources, or forcibly transported to work in manufacturing in other Axis territories. Similarly, colonial powers were able to use resources taken from their territories to supply their armies, however this often had devastating consequences for the regions from which food was redirected, contributing to numerous food shortages and famines across Africa, Asia, and Europe. Men from annexed or colonized territories were also used in the armies of the war's Great Powers, and in the Axis armies especially. This meant that soldiers often fought alongside their former-enemies. Aftermath The Second World War was the costliest in human history, resulting in the deaths of between 70 and 85 million people. Due to the turmoil and destruction of the war, accurate records for death tolls generally do not exist, therefore pre-war populations (in combination with other statistics), are used to estimate death tolls. The Soviet Union is believed to have lost the largest amount of people during the war, suffering approximately 24 million fatalities by 1945, followed by China at around 20 million people. The Soviet death toll is equal to approximately 14 percent of its pre-war population - the countries with the highest relative death tolls in the war are found in Eastern Europe, due to the intensity of the conflict and the systematic genocide committed in the region during the war.

The Holocaust was the systematic extermination of Europe's Jewish population in the Second World War, during which time, up to six million Jews were murdered as part of Nazi Germany's "Final Solution to the Jewish Question". In the context of the Second World War, the term "Holocaust" is traditionally used to reference the genocide of Europe's Jews, although this coincided with the Nazi regime's genocide and ethnic cleansing of an additional eleven million people deemed "undesirable" due to their ethnicity, beliefs, disability or sexuality (among others). During the Holocaust, Poland's Jewish population suffered the largest number of fatalities, with approximately three million deaths. Additionally, at least one million Jews were murdered in the Soviet Union, while Hungary, Latvia, Lithuania, the Netherlands and Yugoslavia also lost the majority of their respective pre-war Jewish populations. The Holocaust in Poland In the interwar period, Europe's Jewish population was concentrated in the east, with roughly one third living in Poland; this can be traced back to the Middle Ages, when thousands of Jews flocked to Eastern Europe to escape persecution. At the outbreak of the Second World War, it is estimated that there were 3.4 million Jews living in Poland, which was approximately ten percent of the total population. Following the German invasion of Poland, Nazi authorities then segregated Jews in ghettos across most large towns and cities, and expanded their network of concentration camps throughout the country. In the ghettos, civilians were deprived of food, and hundreds of thousands died due to disease and starvation; while prison labor was implemented under extreme conditions in concentration camps to fuel the German war effort. In Poland, six extermination camps were also operational between December 1941 and January 1945, which saw the mass extermination of approximately 2.7 million people over the next three years (including many non-Poles, imported from other regions of Europe). While concentration camps housed prisoners of all backgrounds, extermination camps were purpose-built for the elimination of the Jewish race, and over 90% of their victims were Jewish. The majority of the victims in these extermination camps were executed by poison gas, although disease, starvation and overworking were also common causes of death. In addition to the camps and ghettos, SS death squads (Einsatzgruppen) and local collaborators also committed widespread atrocities across Eastern Europe. While the majority of these atrocities took place in the Balkan, Baltic and Soviet regions, they were still prevalent in Poland (particularly during the liquidation of the ghettos), and the Einsatzgruppen alone are estimated to have killed up to 1.3 million Jews throughout the Holocaust. By early 1945, Soviet forces had largely expelled the German armies from Poland and liberated the concentration and extermination camps; by this time, Poland had lost roughly ninety percent of its pre-war Jewish population, and suffered approximately three million further civilian and military deaths. By 1991, Poland's Jewish population was estimated to be just 15 thousand people, while there were fewer than two thousand Jews recorded as living in Poland in 2018.

Most estimates place the total number of deaths during the Second World War at around 70-85 million people. Approximately 17 million of these deaths (20-25 percent of the total) were due to crimes against humanity carried out by the Nazi regime in Europe. In comparison to the millions of deaths that took place through conflict, famine, or disease, these 17 million stand out due to the reasoning behind them, along with the systematic nature and scale in which they were carried out. Nazi ideology claimed that the Aryan race (a non-existent ethnic group referring to northern Europeans) was superior to all other ethnicities; this became the justification for German expansion and the extermination of others. During the war, millions of people deemed to be of lesser races were captured and used as slave laborers, with a large share dying of exhaustion, starvation, or individual execution. Murder campaigns were also used for systematic extermination; the most famous of these were the extermination camps, such as at Auschwitz, where roughly 80 percent of the 1.1 million victims were murdered in gas chambers upon arrival at the camp. German death squads in Eastern Europe carried out widespread mass shootings, and up to two million people were killed in this way. In Germany itself, many disabled, homosexual, and "undesirables" were also killed or euthanized as part of a wider eugenics program, which aimed to "purify" German society.

The Holocaust Of all races, the Nazi's viewed Jews as being the most inferior. Conspiracy theories involving Jews go back for centuries in Europe, and they have been repeatedly marginalized throughout history. German fascists used the Jews as scapegoats for the economic struggles during the interwar period. Following Hitler's ascendency to the Chancellorship in 1933, the German authorities began constructing concentration camps for political opponents and so-called undesirables, but the share of Jews being transported to these camps gradually increased in the following years, particularly after Kristallnacht (the Night of Broken Glass) in 1938. In 1939, Germany then invaded Poland, home to Europe's largest Jewish population. German authorities segregated the Jewish population into ghettos, and constructed thousands more concentration and detention camps across Eastern Europe, to which millions of Jews were transported from other territories. By the end of the war, over two thirds of Europe's Jewish population had been killed, and this share is higher still when one excludes the neutral or non-annexed territories.

Lebensraum Another key aspect of Nazi ideology was that of the Lebensraum (living space). Both the populations of the Soviet Union and United States were heavily concentrated in one side of the country, with vast territories extending to the east and west, respectively. Germany was much smaller and more densely populated, therefore Hitler aspired to extend Germany's territory to the east and create new "living space" for Germany's population and industry to grow. While Hitler may have envied the U.S. in this regard, the USSR was seen as undeserving; Slavs were the largest major group in the east and the Nazis viewed them as inferior, which was again used to justify the annexation of their land and subjugation of their people. As the Germans took Slavic lands in Poland, the USSR, and Yugoslavia, ethnic cleansings (often with the help of local conspirators) became commonplace in the annexed territories. It is also believed that the majority of Soviet prisoners of war (PoWs) died through starvation and disease, and they were not given the same treatment as PoWs on the western front. The Soviet Union lost as many as 27 million people during the war, and 10 million of these were due to Nazi genocide. It is estimated that Poland lost up to six million people, and almost all of these were through genocide.

During the Second World War, the three Axis powers of Germany, Italy, and Finland mobilized the largest share of their male population. For the Allies, the Soviet Union mobilized the largest share of men, as well as the largest total army of any country, but it was restricted in its ability to mobilize more due to the impact this would have on its economy. Other notable statistics come from the British Empire, where a larger share of men were drafted from Dominions than from the metropole, and there is also a discrepancy between the share of the black and white populations from South Africa.

However, it should be noted that there were many external factors from the war that influenced these figures. For example, gender ratios among the adult populations of many European countries was already skewed due to previous conflicts of the 20th century (namely WWI and the Russian Revolution), whereas the share of the male population eligible to fight in many Asian and African countries was lower than more demographically developed societies, as high child mortality rates meant that the average age of the population was much lower.

During the Second World War, the German invasion of Denmark took place on April 9, 1940, as part of Operation Weserübung. The primary aim of this campaign was the annexation of Norway, as control of the Scandinavian coast protected Germany's iron supply from Sweden and gave a tactical advantage for naval operations against the UK. Heavily outmanned and outgunned, the Danish government surrendered within a few hours, and this was the least-costly German invasion of the war (not including Austria), with just 16 Danish military fatalities on the day. Overall, modern estimates suggest that more than 6,600 Danes died as a direct result of the Second World War. Roughly half of these fatalities were civilian deaths, including upwards of 1,000 sailors killed by German submarines, and over 750 resistance fighters. However a significant share of Danes were also killed in the service of both the Axis or Allied Powers.

Danes in the service of Germany Almost one third of Danish fatalities were in the service of the German military, as over 6,000 Danish military volunteered to join the German war effort on the Eastern Front, alongside an unknown number of ethnic German volunteers (possibly 2,000) from Schleswig, along the German border. Almost 500 Danes were also killed for informing or collaborating with German authorities during the occupation; most of these were killed by the resistance during the occupation, although many were also executed after the war's conclusion.

The Danish resistance and the rescue of Denmark's Jews When compared with resistance movements in other countries, the rapid annexation of Denmark and the non-removal of the Danish government by Nazi authorities resulted in the Danish movement developing more slowly. The Danish government discouraged its citizens from rising up, and the restrictions imposed by Germany were initially less severe than in many other territories. However, resistance groups (including many military personnel) quickly formed and relayed a significant amount of information to the Allies in early years, before their actions became more violent in later years. Alongside numerous sabotage and assassination missions, a major operation of the Danish resistance was the rescue of Denmark's Jewish population. In early September 1943, German diplomat Georg Ferdinand Duckwitz learned of Hitler's order to arrest and deport Denmark's Jewish population, and secretly organized their reception in Sweden, before leaking the information to Danish authorities. Just days before the order was given, the resistance, with aid from Danish authorities, Jewish leaders, and many ordinary citizens, then smuggled over 7,000 Danish Jews and their families to Sweden. Several hundred Danish Jews were ultimately transported to concentration camps, although the majority were eventually rescued by the Danish-Swedish "white bus" missions just before the war's end. More than 99 percent of Denmark's Jews would ultimately survive the Holocaust. Duckwitz was named as one of the Righteous Among the Nations by the Israeli government in 1971, however, the Danish resistance requested not to be honored individually by Yad Vashem as theirs was a collective effort.

The German invasion of the Soviet Union, in 1941, resulted in a dramatic rise in infant and child mortality rates. While the war was still ongoing in 1944, in Russia, the proportion of female deaths among children under five years was over 60 percent lower than it had been in the invasion's first year. In 1941, 51 percent of all female deaths were among those under five years old, and 29 percent of all female deaths were among infants below the age of one year. In comparison, the figures for male deaths were slightly lower among infants, as a higher share of the adult male population died as a direct result of the conflict, although the crude death rate (i.e. total number of deaths) was significantly higher in these years than at any other time in Soviet history.

Over the course of the Second World War, approximately 44.5 percent of the Soviet population and 8.7 of Soviet territory was occupied by the Axis forces at some point. Despite being allied in the war's early stages, with both countries invading Poland in 1939 via the Molotov-Ribbentrop Pact, Germany would launch Operation Barbarossa, the invasion of the USSR, in 1941, which would become the largest military invasion in history. Movement of the Eastern Front The surprise invasion began on June 22, and Axis forces caught the Soviets off-guard, quickly pushing their way eastward along a frontline that stretched from the Baltic to Black seas. The length of the front-line allowed Axis forces to execute pincer movements around cities and strongholds, which cut off large numbers of Soviet soldiers from their supply lines, as well as preventing reinforcements; in this process millions of Soviet troops were taken as prisoner. Within three weeks, the Germans had taken much of present-day Poland, Belarus, and the Baltic states, before taking Moldova and Ukraine in September, and pushing into western Russia between September and December. The front lines had reached the outskirts of Moscow by November, before exhaustion and cold weather helped Soviet forces hold the line and stall the German offensive. The Red Army was then able to regroup and turning the Germans' own tactics against them, using two-pronged attacks to encircle large numbers of troops, although harsh weather made this stage of the conflict much slower.

The lines remained fairly static until mid-1942, when the Germans focused their offensive on the south, concentrating on the Caucasian oil fields and the Volga River. By November 1942, Axis forces had pushed into these regions, establishing what would ultimately be the largest amount of occupied Soviet territory during the war. Once again, winter halted the Axis advance, and allowed the Red Army to regroup. Learning from the previous year, the Axis command strengthened their forces near Moscow in anticipation of the Soviet counter-offensive, but were caught off-guard by a second counter-offensive in the south, most famously at Stalingrad. The Battle of Stalingrad would come to epitomize the extreme loss, destruction, and brutality of war on the eastern front, with conflict continuing in the city months after the rest of the Axis forces had been pushed west. As 1943 progressed, the Red Army gained momentum by targeting inferiorly-trained and equipped non-German regiments. The spring then became something of a balancing act for the Axis powers, as the Soviets consistently attacked weak points, and German regiments were transferred to reinforce these areas. In the summer of 1943, the front line was static once more, however the momentum was with the Soviets, who were able to capitalize on victories such as Kursk and gradually force the Axis powers back. By 1944, the Red Army had re-captured much of Ukraine, and had re-taken the south by the summer. When the Western Allies arrived in France in June, the Soviets were already pushing through Ukraine and Belarus, towards Berlin. In August 1944, the last Axis forces were pushed out of Soviet territory, and Soviet forces continued their push towards the German capital, which fell in May 1945. Soviet death toll In addition to the near-five million Soviet troops who died during Operation Barbarossa, millions of civilians died through starvation, areal bombardment, forced labor, and systematic murder campaigns. Due to the nature and severity of Soviet losses, total figures are difficult to estimate; totals of 15-20 million civilians and 7-9 million military deaths are most common. Further estimates suggest that the disruption to fertility, in addition to the high death toll, meant that the USSR's population in 1946 was 40 million lower than it would have been had there been no war.

Over the course of the Second World War approximately 127.2 million people were mobilized. The world's population in 1940 was roughly 2.3 billion, meaning that between five and six percent of the world was drafted into the military in some capacity. Approximately one in every 25 people mobilized were women, who generally served in an administrative or medical role, although hundreds of thousands of women did see active combat. Largest armies In absolute numbers, the Soviet Union mobilized the largest number of people at just under 34.5 million, and this included roughly 35 percent of the USSR's male population. By the war's end, more Soviets were mobilized than all European Axis powers combined. However, in relative terms, it was Germany who mobilized the largest share of its male population, with approximately 42 percent of men serving. The USSR was forced to find a balance between reinforcing its frontlines and maintaining agricultural and military production to supply its army (in addition to those in annexed territory after 1941), whereas a large share of soldiers taken from the German workforce were replaced by workers drafted or forcibly taken from other countries (including concentration camp prisoners and PoWs). Studying the figures The figures given in these statistics are a very simplified and rounded overview - in reality, there were many nuances in the number of people who were effectively mobilized for each country, their roles, and their status as auxiliary, collaborative, or resistance forces. The British Empire is the only power where distinctions are made between the metropole and its colonies or territories, whereas breakdowns of those who fought in other parts of Asia or Africa remains unclear. Additionally, when comparing this data with total fatalities, it is important to account for the civilian death toll, i.e. those who were not mobilized.

Russian estimates suggest that the total population of the Soviet Union in 1941 was 195.4 million people, before it fell to 170.5 million in 1946 due to the devastation of the Second World War. Not only did the USSR's population fall as a consequence of the war, but fertility and birth rates also dropped due to the disruption. Hypothetical estimates suggest that, had the war not happened and had fertility rates remained on their pre-war trajectory, then the USSR's population in 1946 would have been 39 million higher than in reality. Gender differences When it comes to gender differences, the Soviet male population fell from 94 million in 1941, to 74 million in 1946, and the female population fell from 102 to 96 million. While the male and female population fell by 19 and 5.5 million respectively, hypothetical estimates suggest that both populations would have grown by seven million each had there been no war. In actual figures, adult males saw the largest change in population due to the war, as a drop of 18 to 21 percent was observed across the three age groups. In contrast, the adult female population actually grew between 1941 and 1946, although the population under 16 years fell by a number similar to that observed in the male population due to the war's impact on fertility.

As of 2021, there were over 200,000 living United States veterans who served in the Second World War. The Department of Veteran Affairs projects that the number of living veterans will decline rapidly in the fifteen years until 2036, at which point just a few hundred Americans who served in the war will be still alive. The passing of the "Greatest Generation" is seen as symbolic by some, as for many people they represented the era when the United States' power on the world stage was at its greatest. The Second World war is particularly remembered as a "just" war in the U.S., as the United States was seen as fighting for democracy and self-determination, and against the tyrannies of Fascism, Nazism, and Japanese Imperialism.

The United States' involvement in the Second World War

World War II marked the peak in military enlistments in U.S. history, with over 16 million service members serving worldwide during the conflict. The U.S. joined the war in 1941 due to Imperial Japan's attack on the U.S. naval base at Pearl Harbor, Hawaii, before joining the European theater of the war in 1944 during the Invasion of Normandy. The U.S. military played a vital role in the defeat of Nazi Germany on the Western Front in May 1945, while the Soviet Red Army defeated the Wehrmacht in the East. The U.S. was also vital in the defeat of Fascist Italy, as they had led an allied invasion force onto the Italian peninsula from Northern Africa in September 1943. The final action of the war took place in the Asian theater of war, as Imperial Japan was the last of the Axis powers to concede defeat to the Allies. The United States effectively ended the war with the dropping of two nuclear bombs on Hiroshima and Nagasaki in August 1945, leading to as many as a quarter of a million deaths. It remains to this day the sole use of atomic weapons in an active conflict.

Between 1939 and 1950, the Soviet Union's fertility rate underwent the most drastic change of all the major Allied Powers; falling from 4.9 births per woman in 1939 to just 1.7 births in 1943. In Russia alone, this decline was even greater, falling from 4.9 to 1.3 births in the same time period. After the war's conclusion in 1945, there was an observable increase in fertility in all the given countries, and this marked beginning of the global baby boom of the mid-twentieth century.

The worldwide Jewish population experienced a marked decline during the 20th century due to the murder of six million Jewish people during the Holocaust, the genocide perpetrated by Nazi Germany and its allies during World War II. While there were almost 17 million Jewish people alive before the Holocaust, or the Shoah as it is known in Hebrew, after the war this was only around 11.5 million people. By using several different fertility scenarios, demographers have been able to reconstruct what the Jewish population would be in modern times if the genocide of Jewish people had not happened. In scenarios where there was a low or very low fertility rate, the Jewish population in 2000 would be in the range of 26 to 33 million people, double what it was in reality. In a scenario where the population growth rate was the same as that observed in the Jewish population after WWII, which was extremely low, the global Jewish population would have risen to over 20 million people.

The Second World War had a sever impact on gender ratios across European countries, particularly in the Soviet Union. While the United States had a balanced gender ratio of one man for every woman, in the Soviet Union the ratio was below 5:4 in favor of women, and in Soviet Russia this figure was closer to 4:3.

As young men were disproportionately killed during the war, this had long-term implications for demographic development, where the generation who would have typically started families in the 1940s was severely depleted in many countries.

Of the total 127.2 million personnel mobilized during the Second World War, over two thirds of these were on the side of the Allied Powers. This means that there were over two Allied soldiers for every one Axis soldier. Additionally, the populations of the Allied powers were much greater than those of the Axis, and their ability to reinforce and replenish their numbers as the war progressed would be one of the main factors in the eventual Allied victory.

In 1800, the population of the area of modern-day Lithuania was estimated to be just under 780,000. Lithuania’s rate of population growth would remain largely unchanged in the 19th century, as the Russian Empire would slowly but gradually develop its border regions. While large numbers of Lithuanians would emigrate west-ward (largely to the United States) between 1867 and 1868 after a famine in the country, growth would remain largely uninterrupted until the beginning of the First World War in 1912, which would see Lithuania, like much of the Baltic region, devastated as the battleground between the German and Russian Empires. As the conflict spread, those who were not made to evacuate by orders from the Russian government would face economic turmoil under German occupation, and as a result, Lithuania’s population would fall from just under 2.9 million in 1910, to under 2.3 million by 1920.

While Lithuania’s population would start to grow once more following the end of the First World War, this growth would be short-lived, as economic turmoil from the Great Depression, and later occupation and campaigns of mass extermination in the Second World War, most notably the extermination of 95 to 97 percent of the country’s Jewish population in the Holocaust, would cause Lithuania’s population growth to stagnate throughout the 1930s and 1940s. In the years following the end of the Second World War, Lithuania’s population would steadily climb, as industrialization by the Soviet Union would lead to improved economic growth and access to health, and campaigns of mass immunization and vaccination would lead to a sharp decline in child mortality. As a result, by the 1990s, Lithuania would have a population of over 3.7 million. However, Lithuania’s population would rapidly decline in the years following the dissolution of the Soviet Union in 1991, as economic crises and mass emigration from the country, paired with sharp declines in fertility, would result in a dramatic reduction in population. As a result, in 2020, Lithuania is estimated to have a population of just over 2.7 million.

Europe's Jewish population in 1939 was around 9.5 million people, and it is estimated that six million of these were ultimately killed by 1945. The persecution of German Jews escalated during the interwar period, particularly after Hitler's ascent to power in 1933, and again after Kristallnacht in 1938. However, the scale of this increased drastically following the German invasions of Poland in 1939 and the USSR in 1941, when Germany annexed regions with some of the largest Jewish populations in Europe. Extermination Camps As part of the "Final Solution to the Jewish Question", the Nazi occupiers established six extermination camps in present-day Poland; these were Auschwitz-Birkenau, Belzec, Chelmno, Majdanek***, Sobibor, and Treblinka. Prisoners, mostly Jews, were transported from all over Europe to these camps. Upon arrival, the majority of victims were sent directly to purpose-built chambers or vans, where they were murdered with carbon monoxide or Zyklon B gas. A relatively small number of prisoners were also forced to dispose of the victims' bodies, which often included their own family members, friends, or persons known to them. Most of the deceased were incinerated, and many of the camp records were destroyed; this means that precise figures for the number of deaths in extermination camps will never be known. It has been estimated that at least 2.7 million Jews were murdered in these six camps; over two thirds of these were killed at Auschwitz or Treblinka. Einsatzgruppen After extermination camps, the most common method of murder was through mass shootings. The majority of these shootings were not carried out by regular soldiers, but specialized task forces known as "Einsatzgruppen". Each group was just a few hundred men each, but they were responsible for some of the largest individual acts of genocide in the war. The largest of these took place at Babi Yar, near Kyiv in 1941, where almost 35,000 victims were beaten, humiliated, and then shot over a two day period. The Einsatzgruppen were most active in the annexed Soviet territories (although additional regiments were active in Poland and the Balkans), and their ranks were often bolstered by local volunteers. It has been estimated that Einsatzgruppen were responsible for the genocide of more than two million people in fewer than six years.