August 6, 2020, marks the 75th anniversary of the dropping of the first atomic bomb. Two American atomic bombs ended World War II in August 1945, and the devastation will be forever remembered. In an instant when the first bomb was dropped, tens of thousands of residents of Hiroshima, Japan were killed by "Little Boy," the code name for the first atomic bomb used in warfare in world history. It was the first-ever nuclear weapon used in the warfare. The Little Boy bomb was dropped by the Boeing B-29 Superfortress Enola Gay which was piloted by the Colonel Paul W. Tibbets, Junior commander of the 509th Composite Group of the US Army Air Forces and Captain Robert A. Lewis. The Little Boy was developed by Lieutenant Commander Francis Birch's group at the Manhattan Project's Los Alamos Laboratory during the World War II, a reworking of their unsuccessful Thin Man nuclear bomb. Like that of the Thin Man, it was a gun-type fission weapon, but it derived its explosive power from the nuclear fission of uranium-235, whereas Thin Man was based on fission of plutonium-239.