The Type IX U-boat was designed by Nazi Germany's Kriegsmarine in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. It was derived from the Type IA and appeared in various sub-types.
Type IXs had six torpedo tubes; four at the bow and two at the stern. They carried six reloads internally and ten spare torpedoes externally in pressure-tight containers. Type IX boats could also be fitted for mine operations; as mine-layers they could carry 44 TMA or 60 TMB mines.
Secondary armament was provided by one 10.5 cm (4.1 in) deck gun with 180 rounds. Anti-aircraft armament differed throughout the war.