The Manhattan Project:
Was a research and development program, led by the United States with participation from the United Kingdom and Canada that produced the first atomic bomb during World War II. From 1942 to 1946, the project was under the direction of Major General Leslie Groves of the US Army Corps of Engineers. The Army component of the project was designated the Manhattan District; "Manhattan" gradually superseded the official codename, "Development of Substitute Materials", for the entire project. Along the way, the Manhattan Project absorbed its earlier British counterpart, Tube Alloys and operated under a blanket of tight security.
Oppenheimer insisted on a full-scale nuclear test, codenamed "Trinity" on 16 July 1945 the weapon, nicknamed "the gadget" exploded with an energy equivalent of around 20 kilotons of TNT, leaving a crater of Trinitite (radioactive glass) in the desert 250 feet (76 m) wide. The shock wave was felt over 100 miles (160 km) away, and the mushroom cloud reached 7.5 miles (12.1 km) in height. It was heard as far away as El Paso, Texas.
On 6 August 1945 over Hiroshima, Japan an atomic bomb was detonated at an altitude of 1,750 feet (530 m) with a blast that was later estimated to be the equivalent of 13 kilotons of TNT. An area of approximately 4.7 square miles (12 km2) was destroyed. Japanese officials determined that 69% of Hiroshima's buildings were destroyed and another 6–7% damaged. About 70,000 to 80,000 people, or some 30% of the population of Hiroshima, were killed immediately, and another 70,000 injured. On the morning of 9 August 1945, over, Nagasaki a second bomb was dropped The resulting explosion had a blast yield equivalent to 21 kilotons of TNT, roughly the same as the Trinity blast, About 44% of the city was destroyed; 35,000 people were killed and 60,000 injured.