World War II started over Tension between several countries, Japan wanted their Control on Philippines (As they attacked on Pearl Harbor at very first ), Hitler wanted to be a Conqueror, and in turn United States had to participate 'cause they couldn't leave their control on their own teritorry on can't accept others military power in their own area
Throughout most of the war, Lincoln believed that emancipation had to be coupled with the voluntary emigration of freed people out of the United States.
Sources such as diaries though not very reliable can be used if there are a large amount of them showing the same date and event. Historical books written about the event especially those closer to the time would be able to help determine that the date is accurate as well.
