#1
Global depression during the 1930s led to the rise of dictators in Europe and Asia.
#2
Europe first, also known as Germany first, was the key element of the grand strategy agreed upon by the United States and the United Kingdom during World War II. According to this policy, the United States and the United Kingdom would use the preponderance of their resources to subdue Nazi Germany in Europe first.
#3
#4
On April 2, 1917, President Woodrow Wilson went before a joint session of Congress to request a declaration of war against Germany. ... Germany's resumption of submarine attacks on passenger and merchant ships in 1917 became the primary motivation behind Wilson's decision to lead the United States into World War I.
#5
Genocide is the attempted destruction of a people, usually defined as an ethnic, national, racial, or religious group. Raphael Lemkin coined the term in 1944, combining the Greek word γένος (genos, "race, people") with the Latin suffix -caedo ("act of killing").
In 1948, the United Nations Genocide Convention defined genocide as "acts committed with intent to destroy, in whole or in part, a national, ethnic, racial or religious group, as such" including the killing of its members, causing serious bodily or mental harm to members of the group, deliberately imposing living conditions that seek to "bring about its physical destruction in whole or in part", preventing births, or forcibly transferring children out of the group to another group. Victims are targeted because of their real or perceived membership of a group, not randomly.