Commerce raiding is to destroy the logistics (supplies) of an enemy on the open sea, rather than engaging the combatants themselves or enforcing a blockade against them.
Commerce raiding was heavily criticised by the naval theorist A.T. Mahan, who regarded it as a distraction from the destruction of the enemy's fighting power. Nevertheless, commerce raiding was an important part of naval strategy from the Early Modern period through up to and including the Second World War.
Usually, commerce raiding is chosen by a weaker naval power against a stronger, or by a nation with little ocean-going trade against one with a great deal. The best protection against commerce raiding strategy is for merchant vessels to sail in convoy, protected by naval escorts.
This quickly became a major commercial enterprise, with privateer vessels, often in groups, being outfitted by venture capital, with investors also sharing in the returns. The practice rapidly spread. A privateer was distinguished from a pirate by the letter of marque, by which the vessel was commissioned as a private man-of-war. Captured vessels and cargo were submitted, in Britain's case, to Admiralty courts, where they might be condemned for sale, or, if the captures were not found to be within the rules of war, they might be released, sometimes with awards for damages.
Limitations set by the Treaty of Versailles meant that Germany could not build a large battle fleet as it had during WWI, and chose to concentrate on air and land power instead. U-Boats were cheaper and quicker to build than capital ships, and consequently Germany built up submarine rather than surface strength. This meant Germany was not able to fight a war of "guerre d'escadre" (battles between fleets), and therefore pursued guerre de course; what small numbers of surface warships Germany possessed, such as the Deutschland class cruisers, as well as her auxiliary cruisers also participated in this strategy.
During World War II, the United States Navy used its submarine fleet to pursue a merchant war against Japanese shipping, while the US Navy's surface fleets conducted offensive fleet engagements against the Imperial Navy. The bulk of the Japanese merchant marine was sunk by American submarines. By the end of the war, Japan only had 12% of the tonnage of her pre-war shipping afloat.
The Indian Ocean raid was a naval sortie by the Carrier Striking Task Force of the Japanese Navy from 31 March to 10 April 1942 against Allied shipping and bases in the Indian Ocean. It was an early engagement of the Pacific campaign of World War II.
The staff of the Imperial Japanese Navy decided to send some raiders to Indian Ocean waters during December 12,1941-July 12, 1942. The Germans had already been operating in the area and conducted mutual aid with Japanese submarines, in the form of re-supply and military intelligence. The Indian Ocean was the largest operating area involving direct contact between the two axis partners, in which their primary objective was to keep the pressure on the shipping lanes. The Japanese Navy participated in Raider Warfare, but concentrated their powerful fleets on "Guerre d'Escadre", Fleet Warfare in the larger areas of the vast Pacific Ocean.