The object of naval warfare must always be directly or indirectly either to secure command of the sea or to prevent the enemy from securing it.
Julian Corbett, 1911
The Royal Australian Navy suffered its largest loss on 19 November 1941, when HMAS Sydney was sunk by German auxiliary cruiser, HSK Kormoran. This fateful engagement cost 645 Australian (pictured above) and 82 German lives and has puzzled many as Sydney was the superior ship, a battle-hardened and modern cruiser in contrast to the merchant vessel-cum-raider, Kormoran. The enigma is only now being cracked since the discovery of both wrecks in 2008 and 2011.
November 1941 was the beginning of year of heavy losses for the RAN. The loss of Sydney deprived the RAN of warfighting capability against the Imperial Japanese Navy (IJN) when the IJN was superior to Allied forces in the Pacific, and was followed by the loss of sister-ship HMAS Perth in the Sunda Straight in March 1942. Strikingly, while Perth was sunk after sustained action against a large force of Japanese warships, Sydney succumbed to a single auxiliary cruiser. However, Sydney’s loss, while great, is only one impact of German commerce raiders.
Although the U-boats had a greater influence, Germany’s eleven auxiliary cruisers sank or captured 142 Allied ships with more than 872,000 Gross Registered Tonnage (GRT) (Muggenthaler, 1977). The auxiliary cruisers had greater independence and posed a threat to Allied sea lines of communication (SLOC) across the seven seas: Kormoran cruised for eleven months before it was finally sunk, while Altantis covered 160,000km in 602 days (Muggenthaler, 1977). This incredible endurance provided Germany with sea denial capabilities beyond the Atlantic. Their daring voyages through far-flung oceans and exotic ports captured the minds of the German public and their captains, men like Theodor Detmers and Bernhard Rogge, became national heroes. For a while, the mighty Royal Navy seemed entirely incapable of defending against the raiders, which roved freely—albeit, discreetly—through the Commonwealth’s backyard, off the coast of the Atlantic, South Africa and Australia.
Militarily, the raiders tied up Allied resources in pursuit and contributed to the need to adopt a convoy system. However, as the war progressed, the surface raiders became less effective (Cooper, 2001). Convoys, technology and better detection processes diminished the raiders to a nuisance until they were all sunk or removed from service.
So, what was the use and effect of Germany’s surface commerce raiders? The story of the Kormoran is the perfect way to explore this. But first, we must consider commerce raiding as part of a developing German maritime strategy. Then we will assess the use of commerce raiders, including the tactics of deception, targets and Allied responses. Finally, we will evaluate the strategic impact of commerce raiders, both materiel and economic, with particular focus on the loss of Sydney and the Australian war effort.
Commerce raiding in German strategic doctrine
It is productive to consider the context of Germany’s strategy and how auxiliary cruisers fit into it. Maritime strategy formalised during the late 19th century and early 20th century and was dominated by two theorists: American, Alfred Mahan and his 1890 book The Influence of Seapower on History and British, Julian Corbett and his 1911 book Some Principles of Maritime Strategy. These two theorists greatly influenced the development of navies in WW1 and WW2.
Mahan identified six principle conditions determining a nation’s seapower: geographical position, physical conformation, extent of territory, population, character of people and character of government. He argued that the purpose of naval action is the destruction of the enemy fleet and establishment of one’s own control of the sea through decisive battle doctrine (Mahan, 1890). His influence is clear in German naval doctrine in WW1. Admiral Alfred von Tirpitz, father of the German navy, declared in June 1897 that:
“Commerce raiding and transatlantic war against England is so hopeless, because of the shortage of bases on our side and the superfluity on England’s side, that we must ignore this type of war against England in our plans for the constitution of our fleet.” (Parkinson, 2015)
Tirpitz’s rejection of commerce raiding is guided twofold by Mahan. Per Mahan’s geographic principle, Germany in WW1 lacked bases and was easily boxed in. Tirpitz, and most military and political leaders at the time, favoured decisive battle doctrine, both at sea and on land. In the early 1900s, field marshals prophesied rapid, sweeping victories across the Rhine, as had been achieved in the 1871 Franco-Prussian War. Admirals, like Tirpitz, oversaw the build up of immense navies, with unprecedented weaponry, armour and size. Germany was to use its industrial might to furnish the battleships that would obliterate the British, rather than compete in a conflict that relied on the number and location of naval bases, access to coal and depth of naval tradition.
However, decisive battle doctrine failed at the Battle of Jutland, which, despite its scale, was indecisive (Scheer, 2013). At Jutland, 151 British and 99 German ships had joined battle, including an unprecedented 28 British and 16 German battleships. Both sides claimed victory, but although the Germans had outperformed the British, they had failed to break the blockade and could ill afford more such ‘victories’. Following Jutland, German maritime strategy in WW1 focused on U-boats and trade interdiction. The shift to sea denial through commerce raiding largely defined Germany’s interwar strategy. Limitations on size and number of warships imposed by the Treaty of Versailles and the 1935 Anglo-German Naval Agreement further favoured guerre de course (Cribbs, 2004).
Corbett’s influence is clear in Germany’s adoption of sea denial strategy. Corbett argued that “the object of naval warfare must always be directly or indirectly either to secure command of the sea or to prevent the enemy from securing it” (Corbett, 1911). As the Kriegsmarine could not secure sea command, it focused on sea denial (Cribbs, 2004). Auxiliary cruisers, because of their endurance and independence, were ideally suited to Germany’s strategy of a ‘ship in every ocean’. In early WW2, German U-boats were unable to operate beyond the North Atlantic. Given that the Allies possessed large colonial empires, Germany sought to disrupt Allied SLOCs as “by denying an enemy this means of passage we check the movement of his national life at sea in the same way we check it on land by occupying his territory” (Corbett, 1911). Commerce raiding was further supported by two developments: 1940 saw Germany gain numerous bases to operate U-boats and support ships in France and Norway; and the failure of Operation Sea Lion and defeat in the Battle of Britain meant that Germany’s only possible recourse against Britain was at sea, albeit not in battle (Hessler, 1989). Introducing auxiliary cruisers through 1939-42, including Kormoran, coincides with these developments. The auxiliary cruisers were to serve three purposes: interdict and disrupt Allied trade, disperse Allied navies and support the U-boats.
Kriegsmarine doctrine states that cruiser warfare is to “oblige enemy forces to relieve the homeland … force him to convoy and increase the protection of his shipping even in distant waters” thus “increasing the demands on his forces” and “frighten off neutral shipping from sailing in service of the enemy”(Hore, 2001). Doctrine notes that these goals are more important than the number of ships sunk—the strategic effect is greater than the immediate cost of lost cargoes, sailors and ships. This clearly shows the break from earlier Mahanist decisive battle doctrine. Germany recognised the Royal Navy’s superiority and the greater strategic advantage achievable through commerce warfare.
Germany’s use of auxiliary cruisers and Allied responses
Kormoran was originally built for the Hamburg-Amerika Line as an ocean liner, but was taken up by the Kriegsmarine for conversion(Cole, 2009). This work was second in priority only to the U-boats (Detmers, 1959). As the auxiliary cruisers were not armoured warships, they relied on camouflage and deception to avoid Allied warships and prey on merchant vessels. She was fitted with old WW1 guns hidden behind sheet metal and false hull plates. Kormoran had orders to avoid action, even against inferior naval forces, as even minimal damage would reduce the cruiser’s effectiveness (Detmers, 1959). Instead, raiders were to make sudden appearances and disappearances to “cause interruption to the flow of trade, while not unduly risking the existence of the raider” (Hore, 2001).
Deception characterises the battle between Kormoran and Sydney. In fact, the orders given to Detmers, CO Kormoran, specified that “if encounter with the enemy is unavoidable, every attempt to destroy the enemy by means of camouflage, by unexpected and ruthless use of all weapons should be made” (Hore, 2001). Kormoran did exactly this, pretending to be the Dutch merchant vessel Straat Malakka, such that Sydney came within one mile without correctly identifying her, contributing to Kormoran’s success (Cole, 2009). Other deceits were used during Kormoran’s eleven-month voyage. The use of camouflage by warships and auxiliary cruisers rapidly developed in WW2 (Nash, 2014). Camouflage was particularly important for auxiliary cruisers as they lacked the speed (Kormoran had a max speed of 18 knots) and armour to escape or survive engagements.
The threat of auxiliary cruisers disrupted Allied trade beyond their actual ability to sink ships because they forced Allied ships to take less efficient routes. The primary Allied response to commerce raiding was the convoy system. Convoys were safer than sending individual ships, as they were escorted, but they were less efficient because they took longer routes, could go only as fast as the slowest ship, and because ships had to wait in port until enough were ready for the convoy to begin(Sea Power Centre, 2008). The inefficiency of convoys at the end of the war was 20-30% over individual sailing (Sternhell & Thorndike, 1946). However, earlier in the war Allied organisational procedures was worse and inefficiency greater. Thus, although convoys reduced sinking, they came at a substantial cost. The RAN’s response to increased threat around Australia was the first trans-Tasman convoy, Convoy VK1, in December 1940; coastal convoys followed in 1942 (Robinson, 2016). Long before the threat of Japanese midget submarines attacking Sydney Harbour in May 1942, the Australian public was becoming aware that the threat of naval attack was not confined to distant shores.
Aside from establishing convoys, Allied countermeasures included detection and identification processes. Two were technological: ULTRA and radar. ULTRA was signals intelligence and included cracking the Kriegsmarine’s enigma code in June 1941, while the development of centimetric radar allowed for early detection and destruction of German raiders (Hessler, 1989; Brown, 1999). These developments allowed safer passage and contributed to all eleven auxiliary cruisers being either sunk or discontinuing service as raiders by 1943 (Muggenthaler, 1977). When faced with the Allies’ uncanny ability to detect their surface ships, the Kriegsmarine doubled down on U-boats. Another development was better friend/foe identification. Kormoran maintained her disguise long enough for Sydney to approach too close. Following this, the RAN and Allies improved friend/foe identification by using secret codes and assuming action stations earlier when approaching suspicious ships (Hore, 2001).
Strategic impact of the auxiliary cruisers
Commerce raiding and sea denial are usually considered the strategies of weaker naval powers, because they negate some advantages of larger navies and make best use of smaller resources. This is seen with Germany’s auxiliary cruisers. Cheaper and faster to commission than equivalent cruisers, Germany’s eleven auxiliary cruisers had a large, albeit brief, strategic impact. This impact was two-fold: diminished warfighting capability and economic.
The loss of warfighting capability is the main strategic impact of German commerce raiding. Admiral Raeder, head of the Kriegsmarine, sought to diminish Allied local superiority by forcing dispersal in pursuit of German raiders. In October 1939, three British carriers, three battleships and fifteen cruisers were tasked with escorting trade and hunting raiders in the North Atlantic, although at the time only two German ships, the cruisers Admiral Graf Spee and Deutschland were active there (Miller, 1997). Similarly, Sydney withdrew from the Mediterranean in 1941 with orders to escort Australian-bound ships and to protect Australia because of German surface raiders operating in the area (Cooper, 2001). Between August 1940 and November 1941 five surface raiders operated in Australian waters—Orion, Pinguin, Komet, Atlantis and Kormoran. They sunk or captured 20 merchant vessels near Australia, with 111,800 GRT, mined sea-lanes and shelled Nauru, damaging the vital phosphorous plant (Gill, 1957). Australia was targeted because it was inadequately defended by naval and air power, in contrast with the busier and better defended Atlantic, and because its isolation would force a greater dispersal of Allied forces. Thus, Germany sought, and achieved, a withdrawal of Australian naval units from the European theatre by threatening the homeland.
Kormoran’s sinking of Sydney was a substantial windfall for the Axis as its loss deprived Australia of important capability for the rest of the war. Sydney’s loss must be considered in the context of having spent most of 1941 escorting ships; in fact, she was escorting troopship Zeelandia immediately prior to her engagement with Kormoran (Cooper, 2001). Her loss forced the redeployment of HMAS Australia from escort duty in the Atlantic to escorting in the Australia Station. This in turn made German U-boat raiding in the Atlantic more effective (Cooper, 2001). The loss of Sydney also affected Australia’s operations against the IJN in 1942. As one of three light cruisers operated by the RAN in WW2, Sydney’s loss, followed by sister-ship Perth’s in early 1942, left Australia with only one light cruiser, three old heavy cruisers and a mix of destroyers and corvettes to counter the materially superior IJN (Dean, 2013). 1942 was a year of heavy losses for the RAN, increasing its reliance on the USN.
The economic cost of commerce warfare was substantial. Auxiliary cruisers sinking over 872,000 GRT and 142 ships was most important in 1941-42 when Allied losses exceeded ship production and Britain faced shortages of food and fuel(White, 2007). Approximately 10 tons of supplies were necessary to supply a single soldier for a year on the front, so one could interpret that 872,000 tons lost degraded Allied capability to supply 87,200 soldiers for a year – realistically, the disruption was dispersed across the entire economy and war effort (Milward, 1980). In fact, auxiliary cruisers sunk more Allied shipping than did German surface warships (White, 2007). Australia was less severely affected because it had a secure domestic supply of food and other materiel. Shelling Nauru’s phosphorous plants did threaten Australia’s ordnance production, but Australia had stockpiles (Cooper, 2001). More significant was the inefficiency of convoys, disruptions and damaged morale caused by shortages.
In conclusion, Kormoran and other auxiliary cruisers were vital to Germany’s strategy of sea denial and substantially impacted the Allied war effort. Although less significant than U-boats, the superior endurance and disguising of auxiliary cruisers allowed Germany to threaten Allied SLOCs with a ‘ship in every ocean’. This threat, including five such raiders operating in Australian waters, forced a dispersal of Allied ships, the adoption of inefficient convoy systems and a degraded war effort from lost cargoes. While Sydney’s loss with all hands is Kormoran’s most startling success, and diminished the RAN’s capability to resist the IJN, German doctrine realised that the greater strategic impact was forcing the Allies to commit significant resources to counter the relatively cheap surface raiders.
The auxiliary cruisers were most effective between 1940-42. As the war progressed, the Allies developed effective countermeasures, including convoys, ULTRA, radar and friend/foe identification. Even though most auxiliary cruisers were sunk, this essay has argued that they were highly effective for commerce warfare, and that just as German doctrine made best use of the auxiliary cruisers, broader German strategy capitalised on Germany’s strengths since it could not openly compete with the Royal Navy.
Brown, L., 1999. A Radar History of World War II. 1st ed. London: Institute of Physics Publishing.
Cole, T., 2009. The Loss of HMAS Sydney II: Final Report, Canberra: Defence Publishing Service.
Cooper, A., 2001. Raiders and the Defence of Trade: The Royal Australian Navy in 1941. [Online]
Available at: https://www.awm.gov.au/events/conference/2001/cooper.asp
[Accessed 22 March 2017].
Corbett, J., 1911. Some Principles of Maritime Strategy. 1st ed. London: Longmans.
Cribbs, D., 2004. The influence of maritime theorists on the development of German naval strategy from 1930 to 1936. 1st ed. Fort Leavenworth: US Army Command and General Staff College.
Dean, P., 2013. Australia 1942: In the Shadow of War. 1st ed. Cambridge: Cambridge University Press.
Detmers, T., 1959. The Raider Kormoran. 2nd ed. Glasgow: William Kimber.
Gill, H., 1957. Volume 1 – Royal Australian Navy, 1939-1942. 1st ed. Canberra: Australian War Memorial.
Hessler, G., 1989. U Boat War in the Atlantic 1939-1945: German Naval History. 2nd ed. London: HM’s Stationery Office.
Hore, P., 2001. HMAS Sydney II: the cruiser and the controversy in the archives of the United Kingdom. 1st ed. Canberra: Defence Publishing Service.
Mahan, A., 1890. The Influence of Seapower on History. 1st ed. New York: Little, Brown and Company.
Miller, N., 1997. War at Sea: A Naval History of World War II. 2nd ed. Oxford: Oxford University Press.
Milward, A., 1980. War, Economy and Society, 1939-1945. 1st ed. Berkely: University of California Press.
Muggenthaler, A., 1977. German Raiders of World War II. 1st ed. New York: Prentice-Hall.
Nash, J., 2014. Confuse or Conceal – the use of camouflage. Semaphore, Issue 02.
Parkinson, R., 2015. Dreadnought: the ship that changed the world. 1st ed. New York: IB Tauris.
Robinson, S., 2016. False Flags: Disguised German Raiders of World War II. 1st ed. Sydney: Exisle Publishing.
Scheer, R., 2013. Germany’s High Seas Fleet in the World War. 2nd ed. London: Shilka Publishing.
Sea Power Centre, 2008. The Maritime Defence of Australia – 1942. Semaphore, February(03).
Sternhell, C. & Thorndike, A., 1946. Antisubmarine Warfare in World War II, Washington, D.C.: Columbia University Press.
White, D., 2007. Bitter Ocean: The Battle of the Atlantic. 1st ed. New York: Simon & Schuster.