What was the main accomplishment of the manhattan project during world war ii?

The development of the atomic bomb

Explanation:

The Manhattan Project was a research and development project carried out during the Second World War that produced the first nuclear weapons, led by the United States with the support of the United Kingdom and Canada. From 1942 to 1946 the project was under the direction of Major General Leslie Groves of the Army Corps of Engineers of the United States, while the nuclear physicist Robert Oppenheimer was the director of the Los Alamos Laboratory in which the nuclear bombs were designed .