By the end of World War I, the Sopwith Aviation Company and the All British Engine Company (ABC) had worked together for six years making engines and aircraft for the British military. Sopwith executives realized they needed something to sell to civilians to stay in business. In 1918, they bought the rights to ABC’s 400 cc. Unfortunately, the change of producing aircraft to motorcycles was more challenging and expensive than they had expected. By 1923, ABC Sopwith was out of business after making only 2,200 motorcycles.