BMW began in 1916 as an aircraft engine manufacturer for Germany before World War I. The Treaty of Versailles banned the German air force and aircraft in Germany. The first BMW motorcycle was built in 1921 with the M2B15 flat-twin engine. BMW again struggled to re-establish itselft after the Second World War--a war that left Germany in economic and structural shambles. After being allowed permission from U.S. authorities to build motorcycles in 1947, BMW started from scratch and became would evolve into an industry staple for industrial engines, motorcycles and cars.