Complex sentence: From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers; nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs.
Split into simpler sentences: From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the U.S. Army Corps of Engineers. Nuclear physicist J. Robert Oppenheimer was the director of the Los Alamos Laboratory that designed the actual bombs.