The Boeing B-29 Superfortress was the single-largest military project of any nation in World War II (even more expensive than the Manhattan Project). The B-29 was a revolutionary new bomber with a number of novel innovations. It was used to flatten entire Japanese cities and drop atomic bombs on Japan, ending the war. Following its entry into World War II, the United States switched over to a total war economy. The production and sale of new civilian cars were banned, and the nation’s industry was fully dedicated to the war effort.