On July 17, 1944, the weapons on a United States Navy ship exploded. This caused the highest number of deaths at a time among African Americans during World War II. The explosion killed 320 people. The explosion was felt 30 miles away. Later, 258 African American sailors refused to load any more weapons. That was the start of the Navy's biggest-ever mutiny trial. In that trial, 50 men were found guilty. Future Supreme Court Justice Thurgood Marshall was at the trial. He said that he saw a prejudiced court.