
Given the following passage

"After the Holocaust, which had been perpetrated by the Nazi Germany and its allies prior to and during World War II, Lemkin successfully campaigned for the universal acceptance of international laws defining and forbidding genocides. In 1946, the first session of the United Nations General Assembly adopted a resolution that "affirmed" that genocide was a crime under international law, but did not provide a legal definition of the crime. In 1948, the UN General Assembly adopted the Convention on the Prevention and Punishment of the Crime of Genocide (CPPCG) which defined the crime of genocide for the first time.",

answer the following question. Note that the answer is present within the text.

Question: When did Hitler's men initiate and carry out mass genocide, which was later forbidden by the General Assembly?? 

World War II
