There are a number of “outside events” that led to the rise of the Civil Rights Movement and to its success. Let us look at three of the most important.
First, there was World War I and the “Great Migration.” During and after WWI, large numbers of blacks left the South and moved to cities in the North. This was to be very important for the Civil Rights Movement because the movement relied on political support from the North. Northern politicians were willing to support civil rights in part because many of them could benefit from the support of the black voters in that region.
Second, there was World War II. In American rhetoric, this was a war against an evil and racist Nazi regime. The American government emphasized the democratic nature of the United States and contrasted it with the racism and totalitarianism of Nazi Germany. This helped to encourage African Americans to push for the rights that American rhetoric suggested that they should have.
Finally, there was the Cold War. In the Cold War, the US was competing with the Soviet Union for the support of Third World countries made up of non-white people. The lack of civil rights for African Americans made the US look bad and was used by the Soviets against us. This caused many leaders to support civil rights simply to improve the country’s image.
All of these factors helped cause African Americans to feel that they could successfully push for rights in the 1950s and 1960s.