Battle Histories of the IJN's Auxiliary Cruiser Commerce Raiders

27 September 2008

By Bob Hackett, Sander Kingsepp and Peter Cundall

Discussion & Questions

(HOKOKU MARU by Takeshi Yuki scanned from "Color Paintings of Japanese Warships")

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 unavailable.

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 12 of the IJN's Auxiliary Cruisers.

Japanese Auxiliary Cruisers: Tabular Records of Movement (TROMs)

(Auxiliary Classes link to specifications summaries)

Aikoku Maru Class

Hokoku Maru(revised 2/26/05)
Aikoku Maru (posted 3/20/05)
Gokoku Maru (posted 6/25/05)

Kiyosumi Maru Class

Kiyosumi Maru (revised 6/27/07)

Akagi Maru Class

Akagi Maru (posted 1/27/06)

Noshiro Maru Class

Noshiro Maru (posted 10/28/06)

Kongo Maru Class

Kongo Maru (posted 9/27/08)

Asaka Maru Class

Awata Maru (posted 8/7/06)
Asaka Maru

Kinryu Maru Class

Kinryu Maru

Bangkok Maru Class

Bangkok Maru
Saigon Maru

Bibliography of Sources

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.

Questions to the authors concerning these TROMs should be posted on the Discussion and Questions board.