The Bismarck class was a pair of battleships built for the German Kriegsmarine shortly before the outbreak of World War II. The ships were the largest warships built for the German Navy. Bismarck was laid down in July 1936 and completed in September 1940, while her sister Tirpitz's keel was laid in October 1936 and work finished in February 1941. The two ships were broadly similar to the World War I-era Bayern class, in that they mounted a similar main battery and were protected by a similar armour arrangement.