For which war was the 71 calibre tank gun developed by a prominent 400 year old German dynasty?
8.8 cm KwK 43 The 8.8 cm KwK 43 L/71 (Kampfwagenkanone —"fighting vehicle cannon") was an 88 mm 71 calibre tank gun designed by Krupp and used by the German Wehrmacht during the Second World War. It was mounted as the primary armament on the Panzerkampfwagen VI Ausf. B "Tiger II" and the 8.8 cm PaK 43, an anti-tank gun, was very similar in design and use albeit not mounted on tanks but rather on tank destroyers or deployed on the field.
Kaiser-class battleship The "Kaiser" class was a class of five battleships that were built in Germany prior to World War I and served in the Imperial German Navy during the war. They were the third class of German dreadnoughts, and the first to feature turbine engines and superfiring turrets. The five ships were "Kaiser" , "Friedrich der Grosse" , "Kaiserin" , "Prinzregent Luitpold" , and "König Albert" . As was usual for German battleships of the period, the "Kaiser" class mounted main guns that were smaller than those of their British rivals: 30.5 cm , compared to the 34.3 cm guns of the British "Orion" class .