What was Operation Overlord?

Operation Overlord was the code name for the Battle of Normandy, the Allied operation that launched the successful invasion of German-occupied western Europe during World War II. Operation Overlord happened simultaneously with the Normandy landings and the Operation Overlord and was a 1,200 plane airborne assault preceded an amphibious assault involving more than 5,000 vessels. 

African americans at the time just came out of slavery and needed money to provide for there families. so they joined for the money mainly.