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.

With the heightened threat to Germany's Jewish population following the Nazi Party's ascent to power in 1933, many German Jews chose to flee or emigrate. In 1933, Germany's Jewish population was approximately 500,000 people; by the end of the war, it is estimated that 300,000 fled the country, and 165,000 were murdered in the Holocaust. In order to flee, most Jewish emigrants from Germany had to give up the majority of their wealth to the German state, whose emigration tax and seizure of property stripped Jews of their financial assets. Destination and transit For Germany's Jewish refugees, the most common destination country was the United States, and almost half of all these refugees would arrive in the U.S. over this 12 year period. As the United States had a strict quota of 27,000 German migrants per year, many refugees were forced to enter via other countries. France was the second most common destination country, receiving 100,000 refugees. However, France was also used as a transit country for German Jews wishing to travel further afield, especially after it was annexed by Germany in 1940. This was also true for several other European countries, such as the Netherlands, which had provided protection for German Jews in the mid-1930s, before rapidly becoming very unsafe following the outbreak of war in 1939. The Frank family Possibly the most famous example of this was the story of Anne Frank and her family. Anne had been born in Frankfurt, Germany in 1929, but her family moved to the Netherlands in 1934 after Hitler came to power. The family then led a relatively comfortable and successful life in Amsterdam, with her father, Otto, founding his own businesses. When the Netherlands was invaded by the Germans in 1940, the family tried to emigrate once more; Otto had been granted a single Cuban visa in 1942, but the family was forced to go into hiding as the restrictions tightened. For the next two years, with the help of non-Jewish friends, they lived in secret in the upper floor of Otto's business premises with several other Jewish refugees, in a small space concealed behind a bookcase. In August 1944, through unknown means, the group was betrayed and then arrested by Dutch authorities, and the Frank family was sent to Auschwitz-Birkenau thereafter. Anne's mother, Edith, died of starvation in Auschwitz within five months of her capture, while Anne and her sister, Margot, died one month later after being transferred to the Bergen-Belsen camp in Germany. Otto was the sole survivor of the group. Otto's secretary, Miep Gies, had saved Anne's diary the day after the group was arrested, which she then gave to Otto; he then devoted much of the remainder of his life to the publication and promotion of his daughter's diary, which has now become one of the most famous and widely-read books in recent history. Additionally, the hiding space is now open to the public, and has become one of the Netherlands' most popular tourist museums.

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.

Throughout the 19th century, what we know today as Poland was not a united, independent country; apart from a brief period during the Napoleonic Wars, Polish land was split between the Austro-Hungarian, Prussian (later German) and Russian empires. During the 1800s, the population of Poland grew steadily, from approximately nine million people in 1800 to almost 25 million in 1900; throughout this time, the Polish people and their culture were oppressed by their respective rulers, and cultural suppression intensified following a number of uprisings in the various territories. Following the outbreak of the First World War, it is estimated that almost 3.4 million men from Poland served in the Austro-Hungarian, German and Russian armies, with a further 300,000 drafted for forced labor by the German authorities. Several hundred thousand were forcibly resettled in the region during the course of the war, as Poland was one of the most active areas of the conflict. For these reasons, among others, it is difficult to assess the extent of Poland's military and civilian fatalities during the war, with most reliable estimates somewhere between 640,000 and 1.1 million deaths. In the context of present-day Poland, it is estimated that the population fell by two million people in the 1910s, although some of this was also due to the Spanish Flu pandemic that followed in the wake of the war.

Poland 1918-1945

After more than a century of foreign rule, an independent Polish state was established by the Allied Powers in 1918, although it's borders were considerably different to today's, and were extended by a number of additional conflicts. The most significant of these border conflicts was the Polish-Soviet War in 1919-1920, which saw well over 100,000 deaths, and victory helped Poland to emerge as the Soviet Union's largest political and military rival in Eastern Europe during the inter-war period. Economically, Poland struggled to compete with Europe's other powers during this time, due to its lack of industrialization and infrastructure, and the global Great Depression of the 1930s exacerbated this further. Political corruption and instability was also rife in these two decades, and Poland's leadership failed to prepare the nation for the Second World War. Poland had prioritized its eastern defenses, and some had assumed that Germany's Nazi regime would see Poland as an ally due to their shared rivalry with the Soviet Union, but this was not the case. Germany invaded Poland on September 1, 1939, in the first act of the War, and the Soviet Union launched a counter invasion on September 17; Germany and the Soviet Union had secretly agreed to do this with the Molotov-Ribbentrop Pact in August, and had succeeded in taking the country by September's end. When Germany launched its invasion of the Soviet Union in 1941 it took complete control of Poland, which continued to be the staging ground for much of the fighting between these nations. It has proven difficult to calculate the total number of Polish fatalities during the war, for a variety of reasons, however most historians have come to believe that the figure is around six million fatalities, which equated to almost one fifth of the entire pre-war population; the total population dropped by four million throughout the 1940s. The majority of these deaths took place during the Holocaust, which saw the Nazi regime commit an ethnic genocide of up to three million Polish Jews, and as many as 2.8 million non-Jewish Poles; these figures do not include the large number of victims from other countries who died after being forcefully relocated to concentration camps in Poland.

Post-war Poland

The immediate aftermath of the war was also extremely unorganized and chaotic, as millions were forcefully relocated from or to the region, in an attempt to create an ethnically homogenized state, and thousands were executed during this process. A communist government was quickly established by the Soviet Union, and socialist social and economic policies were gradually implemented over the next decade, as well as the rebuilding, modernization and education of the country. In the next few decades, particularly in the 1980s, the Catholic Church, student groups and trade unions (as part of the Solidarity movement) gradually began to challenge the government, weakening the communist party's control over the nation (although it did impose martial law and imprison political opponent throughout the early-1980s). Increasing civil unrest and the weakening of Soviet influence saw communism in Poland come to an end in the elections of 1989. Throughout the 1990s, Poland's population growth stagnated at around 38.5 million people, before gradually decreasing since the turn of the millennium, to 37.8 million people in 2020. This decline was mostly due to a negative migration rate, as Polish workers could now travel more freely to Western Europea...

In the year 1800, the population of the region which makes up the present-day Netherlands was approximately two million people. The beginning of the 19th century was a tumultuous time in Dutch history, as the region had recently been annexed by Revolutionary France; however the United Kingdom of the Netherlands was eventually established in 1815 (which also included present-day Belgium and Luxembourg) and a period of economic growth, modernization and high quality of life followed. In spite of this economic prosperity, religious tensions between the predominantly Catholic south and Protestant north led to a split in the kingdom in 1839, where it was eventually partitioned into Belgium, Luxembourg and the Netherlands, along borders very similar to today's. Rapid modernization and liberalization continued throughout the 19th century, and in 1900 the population of the Netherlands was over five million people.

Early 20th century The Netherlands was free to continue economic expansion, both in the metropole and in its colonies, uninterrupted for much of the first half of the 20th century (partly facilitated by its neutrality in the First World War). This resulted in a steady rise in population, which doubled to ten million within half a century. Population growth would even continue throughout the Second World War, as the Netherlands would be spared from much of the casualty-heavy conflicts seen in neighboring countries; however, most estimates concur that approximately 210,000 Dutch people died as a result of the war, half of which were Jews murdered in the Holocaust. The war also saw the end of Dutch colonization in the East Indies, as Japan annexed the region of present-day Indonesia in 1942; although the Dutch tried to re-colonize the region after the war, Indonesia became an officially recognized independent nation in 1949.

Netherlands today Population growth in the Netherlands would continue largely uninterrupted in the post-war years, until the 1970s, when it began to slow as Western Europe experienced periods of recession and high unemployment. Improvements in contraceptives and education also saw birth rates fall at their fastest ever rates in the 1970s. Following the recovery of the Dutch economy in the 1990s, population growth would resume once more, continuing steadily into the 21th century. In 2020, the Netherlands is estimated to have a population of just over 17 million people, making it one of the most densely populated countries in the world. For its size, the Netherlands has one of the strongest economies globally, and often ranks among the highest in terms of development, freedom and quality of life.