High Quality Content by WIKIPEDIA articles! The O class was a planned class of three battlecruisers for the Kriegsmarine (German Navy) before the Second World War. Prompted by a perceived lack in ship numbers when compared with the British Royal Navy, the O class` design was born with the suggestion of modifying the P class cruiser design with 380 mm (15 in) guns instead of 283 mm (11.1 in). The ships were incorporated into the 1939 Plan Z; while an aircraft carrier, H class battleships and smaller ships engaged convoy escorts, one or more O class ships would attack the merchant ships.