When did the Manhattan Project begin?

Answer 1

While considerable scientific and theoretical work had begun as early as
1939, the Army Corps of Engineers set up the Manhattan Engineer
District in August of 1942 and advanced Colonel Leslie R. Groves to the
rank of Brigadier General one month later and placed him in charge.
Groves was responsible for establishing the Oak Ridge site and Los
Alamos, but the scientific effort was led by J. Robert Oppenheimer.

Answer 2

The Manhattan Project officially started on 28 June 1941. This was the date that President Roosevelt signed the Executive Order that created the Office of Scientific Research and Development. It began research on that date into atomic weapons. This research was eventually named The Manhattan Project.

Answer 3

The Manhattan was officially begun on September 23, 1942, when Col. Leslie Groves was placed in charge of the project.

Answer 4

The Manhattan project was started in 1942. It succeeded and the project was ceased on December 31 1946.

Answer 5

The Manhattan Project was during the 1930's.