Birmingham Small Arms Company (BSA) made motorcycles from 1910 until the end of the marque in the 1970s. 1910 saw entry into market. First model had vertically-mounted 3.5hp engine, chain-driven magneto, sprung forks and excellent finish. During World War I, production ceased while they pursued their traditional manufacturing, making guns, but returned quickly after the war. In 1939 BSA became the largest motorcycle company in the world between the wars. The company owned 67 factories across the UK. During WW2, they made 126,000 M20 motorcycles - among their other war production. By 1961, BSA employs 4,300 people. The 1971 lineup saw major makeovers, including oil-in-frame 650cc twins. BSA was bought by Norton and absorbed into the Norton-Villiers-Triumph group in 1971, which managed to design a A65 Lightning before BSA collapsed. In 1973 the name was finally abandoned and production ended.