- "The Manhattan Project took a lot out of both of us."
- —Talking to Emmett Brown
Leslie Groves, of the U.S. Army Corps of Engineers, led the Manhattan Project. He had the rank of Major General during his time on the Manhattan Project. After the war, he was promoted to the rank of Lieutenant General.
In 1962, Groves and Colonel Lomax came to Emmett Brown with the hope that he could invent machine that would allow time travel, so they could prevent the Cuban Missile Crisis from ever happening. After having regrets about accepting their offer, Doc used his prototype temporal field capacitor to send a message to himself in the past. This caused an electrical fire, which burned down the Brown family mansion. As Lomax and Groves believed him to be an insurance thief, the fire prevented Groves from ever asking Emmett about time travel.
Lomax and Groves then went to another scientist, Marcus Irving, letting him believe that he was their first choice for the project. Irving agreed to the project, and spent 24 years working on time travel. He could never solve the problem of excess flux energy, so his time experiments were never a complete success. Finally, in January 1986, government funding for Irving's project was terminated.
Irving then sought to find out everything he could about the project, and discovered that he was not the first choice. He was jealous of Emmett Brown, for turning them down and for causing him to waste 24 years of his life. While tracking down Doc Brown, Irving discovered that he had built a working DeLorean time machine. He sabotaged the DeLorean and used Doc's design to build a flux capacitor, enabling him to travel through time as well.