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.

The American Civil War is the conflict with the largest number of American military fatalities in history. In fact, the Civil War's death toll is comparable to all other major wars combined, the deadliest of which were the World Wars, which have a combined death toll of more than 520,000 American fatalities. The ongoing series of conflicts and interventions in the Middle East and North Africa, collectively referred to as the War on Terror in the west, has a combined death toll of more than 7,000 for the U.S. military since 2001. Other records In terms of the number of deaths per day, the American Civil War is still at the top, with an average of 425 deaths per day, while the First and Second World Wars have averages of roughly 100 and 200 fatalities per day respectively. Technically, the costliest battle in U.S. military history was the Battle of Elsenborn Ridge, which was a part of the Battle of the Bulge in the Second World War, and saw upwards of 5,000 deaths over 10 days. However, the Battle of Gettysburg had more military fatalities of American soldiers, with almost 3,200 Union deaths and over 3,900 Confederate deaths, giving a combined total of more than 7,000. The Battle of Antietam is viewed as the bloodiest day in American military history, with over 3,600 combined fatalities and almost 23,000 total casualties on September 17, 1862. Revised Civil War figures For more than a century, the total death toll of the American Civil War was generally accepted to be around 620,000, a number which was first proposed by Union historians William F. Fox and Thomas L. Livermore in 1888. This number was calculated by using enlistment figures, battle reports, and census data, however many prominent historians since then have thought the number should be higher. In 2011, historian J. David Hacker conducted further investigations and claimed that the number was closer to 750,000 (and possibly as high as 850,000). While many Civil War historians agree that this is possible, and even likely, obtaining consistently accurate figures has proven to be impossible until now; both sides were poor at keeping detailed records throughout the war, and much of the Confederacy's records were lost by the war's end. Many Confederate widows also did not register their husbands death with the authorities, as they would have then been ineligible for benefits.

The Empire of Japan's military losses in the Second World War are estimated to exceed 2.5 million men. For Japan, the costliest front in the Pacific theater was the battle against the United States in the Philippines, closely followed by its invasion of China, known as the Second Sino-Japanese War. After 1941, the Imperial Japanese Army was simultaneously stretched across several frontlines in the Pacific theater, and this was one contributing factor to their eventual defeat as reinforcing and supplying various armies across these fronts was unfeasible in the long-term.

Although the Japanese invasion of China, known as the Second Sino-Japanese War, lasted for more than eight years, it was the battle against the United States and local defenses for control of the Philippines that resulted in the largest share of Japan's military losses in the Second World War. The Japanese invasion of the Philippines began on December 8, 1941, on the same day as the attack on Pearl Harbor. The Japanese were able to take de facto control of the region by May 1942. Japan faced strong, underground resistance from locals in the two years that followed, until the U.S. military began its counteroffensive in the Leyte Gulf in October 1944, which continued until the war's end. Around 420,000 of the 490,000 Japanese deaths in the Philippines occurred during the Second Philippines Campaign (after Oct. 1944), although some estimates suggest that up to 80 percent of these deaths were due to starvation and malnutrition, as the Japanese supply lines became overstretched in the war's latter phase and failed to provide sufficient food and medicine to its forces.

During the World War II and Korean War era, the U.S. military freely distributed cigarettes to overseas personnel and provided low-cost tobacco products on domestic military bases. In fact, even today the military continues to sell subsidized tobacco products on its bases. Using a variety of instrumental variables approaches to deal with nonrandom selection into the military and into smoking, we provide substantial evidence that cohorts with higher military participation rates subsequently suffered more premature mortality. More importantly, we show that a large fraction, 35 to 79 percent, of the excess veteran deaths due to heart disease and lung cancer are attributable to military-induced smoking.

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.

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.

In 2024, there were no operational deaths in the British Armed Forces, compared with one in 2023. Since 1945, the deadliest year for British Armed Forces was 1951 when there were 851 operational deaths. This was due to three separate conflicts: the Malayan Emergency, the 1951 Anglo-Egyptian War and the Korean War. Between 1959 and 2009 there were only three years that had more than 100 operational deaths: 1972, 1973 and 1982. The spike in deaths in the early 1970s were the result of the political violence in Northern Ireland at the time, and 237 of the 297 deaths in 1982 happened during the Falklands War. Over this period, there have been a total of 7,193 British military deaths in conflicts. Size of armed forces at a historic low in 2024 The British Armed Forces are composed of three main separate branches, the British Army, the Royal Navy, and the Royal Air Force. Of these branches, the British Army has more personnel than the other two combined at around 75,300. The Royal Navy and Marines had 32,000 personnel, while the Royal Air Force had 30,800 active personnel. This was the fewest number of personnel in modern times, and is partly explained by previous modernization efforts, which sought to de-emphasize the importance of a large army based on manpower in favor of a more advanced one based on technology. Long-term defense cuts   These cutbacks in personnel are also a result of the UK government spending far less on defense than it used to. In 1984, for example, the UK spent around 5.5 percent of GDP on defense, compared with just 2.3 percent in 2021. The end of the Cold War in the early 1990s made it difficult to justify 1980s-levels of military spending during this time period, along with the UK having far fewer overseas commitments than in the past. Russia's full-scale invasion of Ukraine in 2022, however, looks set to reverse this trend, with many NATO allies pledging to increase their defense budgets in light of the new geopolitical situation.

When the Winter War broke out between Finland and the Soviet Union in late 1939, international attention turned to the Nordic countries. The neutral country of Norway in particular held strategic importance for Germany, not only due to its naval access to the Atlantic, but also as it was the most efficient route for the transport of Swedish iron to Germany. Norway had the fourth largest shipping fleet in the world, and both sides knew that control of Norway would significantly impact the German war effort; Britain and France had planned a preemptive invasion of Norway in early 1940, however Germany acted faster. Invasion On April 9, 1940, Operation Weserübung was launched, which was the simultaneous invasion of Denmark and Norway. Norway was very unprepared for the surprise attack, and Germany's prioritization of Norwegian air and naval bases hindered the response further. The rapidity of the invasion saw Denmark capitulate within a few hours, and Germany quickly took control of several Norwegian cities with little difficulty. It took several days for the Norwegian military to regroup and coordinate a response. With the help of an Allied expeditionary force and the British Navy, it achieved some success in the North Sea, but the delay had allowed enough time for German armored reinforcements to arrive and secure control of south and central Norway. By early May, most of the fighting had been pushed north, especially around Narvik; the main port for Swedish iron exports to Germany. Narvik was actually re-taken by the Allies on May 28, before they withdrew from Norway 10 days later to support the defense of France. Norway's king and government then left for London, where they formed a government-in-exile, and the final Norwegian military units surrendered on June 10 (after much of their resources were sent to Britain). Despite it taking just two months, the German invasion of Norway was the longest of any in Western Europe. Occupation Germany had planned on allowing the Norwegian government to remain in power (as in Denmark), to legitimize the occupation, but it quickly became clear that this would not be the case. Administrative councils were created, and a puppet government eventually installed, but ultimate control lay with the SS. The occupying force of more than 340,000 German troops was one of the largest per capita forces of the war, and, with hindsight, German investment in Norway's defense far outweighed its eventual use. The Norwegian underground resistance was very active throughout the war, both on land and at sea, and was responsible for some of the most effective sabotage missions carried out against Germany. The Norwegian economy, which had been dependent on international trade, was redirected towards the German war effort and it then shrunk massively. For Norway's citizens, restrictions were less strict than in other territories, but thousands of perceived opponents were still imprisoned or executed, and acts of terror were common. Around two thirds of Norway's Jewish population fled (mostly to Sweden) or went into hiding. However 773 were arrested and deported to concentration camps in Eastern Europe; the majority of these prisoners eventually perished in Auschwitz, and just 38 returned after the war. Liberation As the Soviets pushed the Germans back through Scandinavia in late 1944, German forces adopted a scorched-earth policy as they moved through the northern region of Finnmark. Thousands of homes were burned, and as many as 25,000 Norwegians were forced to live in the wilderness throughout the winter. In November 1944, exiled Norwegian troops and police officers arrived in Russia to take back Finnmark and rescue its citizens; the area was secured by the time of Germany's surrender on May 8, 1945. At the time of surrender, the resistance helped coordinate an effective and generally peaceful transfer of power, before the king and government's return on June 7. Immediately after the war, there were over 140,000 displaced foreigners in Norway, over half of which were Soviet prisoners of war, and over 90,000 displaced Norwegians abroad, mostly in Sweden. Norwegian authorities also investigated 92,000 cases of collaboration, which resulted in 46,000 convictions, 18,000 imprisonments, and 25 executions of Norwegian citizens. Estimates of total Norwegian deaths due to the war are generally around 10,000, although a precise breakdown for the fatalities remains unclear.

After the Second World War, the deadliest conflict for the British Armed Forces was the Malayan Emergency, which lasted from 1948 to 1960 and resulted in the deaths of 1,442 British soldiers. Over a much longer time period, between 1968 and 2007, there were 1,441 operational deaths for the British Armed Forces in Northern Ireland. The Korean War was a noticeably deadly conflict despite its relatively short duration, and had the third-highest number of fatalities for British troops at 1,129. The wars of decolonization The rapid disintegration of the British Empire after 1945 is the cause of many of the conflicts displayed here. In the aftermath of World War Two, there were 70 modern-day countries in the British Empire, but by 1997, Britain’s colonial Empire had vanished. The Palestinian Emergency, which after 1945 caused 754,000 British casualties, as well as the aforementioned Malayan Emergency are just some examples of Britain’s disorderly withdrawal from regions it once controlled. Although the UK won the Falklands War in 1982, the UK's armed forces suffered 237 operational deaths in the ten-day conflict. Recent conflicts The UK armed forces have been involved in several more recent military conflicts, and the deadliest of these was by far the War in Afghanistan, which was responsible for 457 British fatalities. The UK’s involvement in the fight against ISIS in Iraq and Syria is also ongoing, although unlike the Iraq War that took place between 2003 and 2011, where the UK suffered 178 operational deaths, the conflict is fought primarily by the air force. Although no UK soldiers are fighting the War in Ukraine, the UK government has provided extensive equipment and training to the Ukrainian armed forces since 2022, along with several other western nations.  

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.

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.

Throughout the period in which the United States was in an armed conflict with the Communist-led government and insurgency in Vietnam (referred to as the "Vietnam War" in the U.S. and the "Resistance War against the United States" in Vietnam), around 40 percent of the 8.7 million U.S. military service personnel were stationed in South-East Asia. Of these personnel in the theatre of war, around two percent were killed during the conflict.

This war was part of the wider Cold War of the second half of the 20th century, where the rivalry between the superpowers of the United States and Soviet Union dominated the post-World War II era. During this period the U.S. stationed much of its remaining five million service personnel outside of active conflict zones, especially in strategically important countries such as (West) Germany, South Korea, and Japan, in addition to those stationed at home.

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.

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.

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.

1941 marked an escalation of the Second World War in Europe. By the middle of the year, Germany and its European allies had already consolidated power across most of the continent, with only the United Kingdom and Soviet Union not under Axis control or on neutral terms with Germany. As population sizes were fundamental to the war effort, both in terms of military manpower and the workforce of the home front, the annexation of other countries proved vital in supplying new volunteers, conscripts, and forced laborers for the Axis war effort. Together, Germany and Austria had a similar population to the rest of Europe's Axis powers combined, with all giving a total population of 154 million. However, the total population of the Axis-occupied territories in Europe was comparable to the Axis home fronts themselves, at almost 130 million people

Germans in the East Eastern Europe had a sizeable population of ethnic Germans who often worked with the Axis powers, and the German Army recruited upwards of a million volunteers from occupied countries. The Soviet Union in particular had a number of Russia German enclaves across the region, that reached as far as the Volga river and Kazakhstan and numbered at several million people. In Russia, these communities had existed for centuries, but they were ostracized or mistrusted by Soviet leadership and the deaths of these communities under Stalin's regime is often considered genocide. In addition to ethnic Germans, collaborators also included large numbers of Eastern Europeans who sympathized with Nazi ideology, or were hostile to Soviet or communist expansion; this also included ethnic minorities, such as Muslims from the Balkans or USSR.

Collaborators in the West The perceived threat of communism in the west saw men volunteer from countries such as France, the Netherlands, or Norway, to fight in the Axis armies. The fluctuating borders of the interwar period also meant that there were many German communities across the borders of neighboring countries, whose men also enlisted in the Wehrmacht. Within these occupied countries, conspirators with local knowledge were used to track down Jews and political adversaries, and many collaborated in order to elevate their positions in the government or enterprises. Apart from Austria, however, the majority of the public in annexed territories were unsupportive or hostile to their occupiers, and after the war, many of the surviving collaborators were tried (and often executed) for their actions.