From Wikipedia: Douglas Aircraft:
The Douglas Aircraft Company was an American aerospace manufacturer, based in Long Beach, California. It was founded in 1921 by Donald Wills Douglas, Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas. It is currently a part of Boeing's Commercial Airplanes division.
Douglas was a pioneer in .. fields, such as ejection seats, air-to-air, surface-to-air, and air-to-surface missiles, launch vehicles, bombs and bomb racks. Douglas was eager to enter the new missile business in the 1950s. Douglas moved from producing air-to-air rockets and missiles to entire missile systems under the 1956 Nike program and becoming the main contractor of the Skybolt ALBM program and the Thor ballistic missile program. Douglas also earned contracts from NASA, notably for designing the S-IVB Stage of the enormous Saturn V rocket.
In 1967, the company was struggling to expand production to meet demand for DC-8 and DC-9 airliners and the A-4 Skyhawk attack plane. Quality and cash flow problems, combined with shortages due to the Vietnam War, led Douglas to agree to a merger with McDonnell Aircraft Corporation to form McDonnell Douglas. Douglas Aircraft Company continued as a wholly owned subsidiary of McDonnell Douglas, but its space and missiles division became part of a new subsidiary called McDonnell Douglas Astronautics Company.
McDonnell Douglas later merged with Boeing in 1997. Boeing combined the Douglas Aircraft Company with the Boeing Commercial Airplanes division, ending more than seventy-five years of Douglas Aircraft Company history.