One of the scientists hired to work on the Manhattan Project was Emmett Brown, who was hired in 1943, during his tenure as a professor at the California Institute of Technology. Doc had heard of a top secret project to benefit the war effort, and had managed to convince Robert Millikan, the president of Caltech, to arrange an interview with Major General Leslie Groves and Vannevar Bush. Despite a disastrous interview, he was awarded the position.
His part in developing the nuclear bomb, and in bringing in the nuclear arms race of the decades long Cold War that began after World War II ended, would haunt Doc for decades.
In 1944, Marty McFly and Verne Brown arrived to find Doc's Fance-O-Dance dancing shoes. Marty accidentally ended up in the army, leaving Verne to help get him out. The next day, Verne and his friend Dorothy (his dance teacher in 1992) provided a distraction for by entering in a dance, while Marty eluded Frank Tannen.