Used primarily in the European Theater of Operations during World War II, the four-engined heavy bomber also saw action in the Pacific. Built by Boeing (and designed), Lockheed and Douglas Aircraft Corporation, over 12,000 bombers were built before ending production in 1945. While most bombers were victims of a good chance of being shotdown, the B-17 earned its moniker, "The Flying Fortress," with the aircraft's ability to sustain heavy damage in battle. The ability to fly at high-altitude also kept the bomber out of reach of enemy's antiaircraft artillery while delivering 4,000 pounds of bombs on long-runs and up to 8,000 pounds on short-run campaigns.