Millions died in the six-year long war. millions of European Jews also lost their lives at the hands of Nazi forces. As Europe was the catalyst and precursor to the war, it also suffered the most casualties.
The onset of WWII is widely attributed to the German invasion of Poland on September 1, 1939. If taken on a global scale, Manchurian war precedes this even but its geographical location outside of Europe excludes it from this deliberation. Immediately after the invasion of Poland, United Kingdom and France jumped into the war theatre and started their offensive against Germany on Sept. 3. This event was the precursor to the six-year long “war of wars” that engulfed the whole world in its flames.
Germany suffered heavily during the First World War and lost its sovereignty over a significant area of Eastern Europe. In addition to its shameful defeat, allied forces also forced Germany under the Treaty of Versailles to pay magnanimous reparation to the victims of its war crimes (the list included the countries suffered from German atrocities). There were limitations on the establishment of armed forces and development of weapons. Additionally, the country also faces many financial and economic sanctions that damaged its domineering role in Central and Eastern Europe. The German government was weak and the onset of Great Depression in the 1930s eroded its popularity in the masses. Germans were looking for a leader that can take them back to their glorious past with immense prosperity. Adolf Hitler rode high on these emotions and his National Socialist Party clinched the 1933 elections. making him the Chancellor of the Third Reich.
Germany under Hitler saw a relative prosperity and exaltation among the German citizens. this of course excluded Jews and minorities as they started feeling the heat of German nationalism.