The Opelwerk Brandenburg (Opel's manufacturing plant at Brandenburg an der Havel) was built, with impressive speed, in 1935 on the initiative of the government in order to ensure supplies of Opel trucks for the army. Opel were an obvious candidate for the project, having pioneered mass production techniques in German passenger car production at their Rüsselsheim plant: by the late 1920s the company held more than 25% of the domestic passenger car market.