There are at least three ways in which World War II helped to lead to the Civil Rights Movement.
First, the rhetoric of America’s involvement in WWII helped to make it seem more important to give equal rights to African Americans. During WWII, the US played up the fact that it was an inclusive democracy that was fighting against a racist, fascist, dictatorship in Nazi Germany. US propaganda emphasized the multi-ethnic nature of the United States and its inclusive democracy. By emphasizing this aspect of our country, the government was implying that it was important to allow all people to have equal rights. After the war, African Americans did not simply forget this idea.
Second, World War II involved large numbers of African Americans fighting for their country. They were often treated very poorly while in uniform, but they still served. These people, as well as many of their fellow African Americans, came to feel that they had paid their dues for the country and deserved to be treated well.
Finally, WWII brought about changes in the geography of the US. Blacks had been moving north ever since WWI, but the pace picked up during WWII. This meant that, after the war, there were many more African Americans in parts of the country where they were allowed to vote. Their votes became important to some politicians and those politicians came to be more sympathetic to their needs. This helped to push the Civil Rights Movement forward.
In these ways, WWII sent messages to African Americans that they should be free and it encouraged them to move to places where they had more political influence. These things helped the Civil Rights Movement to emerge.
The civil rights movement comprised efforts of grassroots activists and national leaders to obtain for African Americans the basic rights guaranteed to American citizens in the Constitution, including the rights to due process and "equal protection of the laws and the right to vote. Although the 1950s and 1960s represent the height of the mass civil rights movement of the twentieth century, activists had sought basic rights for African Americans since before the Civil war so all of the efforts of the civil rights movement was one of the major ways of the cause of world war 2. Second, nearly one million African Americans served in the armed forces, which needed so many fighting men that they had to end their discriminatory policies.