Battle Histories of the IJN's Auxiliary Cruiser Commerce
20 July 2017
By Bob Hackett, Sander Kingsepp and Peter
(HOKOKU MARU by Ueda Kihachiro)
Auxiliary cruisers were merchant ships converted into armed vessels
and employed either for convoy protection or commerce raiding. In the latter
role, they were disguised as merchant ships, but equipped with hidden
cruiser-size guns, false funnels, torpedo tubes, mines, floatplanes for
scouting and wore false colors, markings and flags. Their appearance was used to
trick enemy merchant ships into approaching thinking they were but harmless
steamers. Their speed, combined with their floatplanes, enabled them to search
large areas of ocean for prey. Once located, the auxiliary cruiser's big guns
could defeat any merchant or smaller combatant.
Early in World War I, Germany used several merchant raiders, the most
successful being MOWE, WOLF and SEEADLER. MOWE sank or damaged a battleship and
42 merchant ships. WOLF remained at sea for a record fifteen months, sinking or
damaging 32 ships. In all, Germany's WW1 raiders sank over 300,000 tons of
Allied shipping. Each also sent back to Germany valuable captured prize ships
containing materials such as rubber, whale oil, and titanium that was otherwise
The success of the German raiders in the First World War was not lost on
the Japanese. In 1941, AIKOKU and HOKOKU MARUs, two passenger-cargo vessels
built for the Osaka Shipping Lineís South America route, were requisitioned for
conversion to armed merchant cruisers (AMC).
Before and during the Pacific War, Japan converted 14 merchants to AMCs.
Although two of these ships initially enjoyed some successes, the early sinking
of HOKOKU MARU and the pressing need for more transports to support their
far-flung Pacific empire resulted in the reconversion of most of Japanís AMC
fleet. By the end of 1943, five of their AMCs had been sunk and seven
reconverted. The remaining two were lost in 1944.
Unlike the Kriegsmarine's raider ATLANTIS, that stayed at sea 622 days in
World War II and sank or captured 23 ships of 145,697-tons, most Japanese AMCs
had but short and undistinguished careers. This page will cover all 14 of the
IJN's auxiliary cruisers.
Japanese Auxiliary Cruisers: Tabular Records of Movement
(Auxiliary Classes link to specifications
About the Authors
Mr. Robert Hackett is a military historian and researcher.
Retired from the United States Air Force and later from the aerospace industry,
he resides in the United States.
Mr. Sander Kingsepp, a native of Estonia, is also a military historian and
researcher. A talented linguist, Sander's translations of Japanese source
materials have greatly enhanced these TROMs.
Mr. Peter Cundall is a maritime historian and researcher who specializes in
merchant ships. He resides in Australia and works in the maritime industry.
Questions to the authors concerning these TROMs should be posted on the
Discussion and Questions board.