Commerce raiding Commerce raiding is a form of naval warfare used to destroy or disrupt logistics of the enemy on the open sea by attacking its merchant shipping , rather than engaging its combatants or enforcing a blockade against them . It is also known , in French , as guerre de course ( literally , " war of the chase " ) and , in German , Handelskrieg ( " trade war " ) , from the nations most heavily committed to it historically as a strategy . 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 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 a commerce raiding strategy is for merchant vessels to sail in convoy , protected by naval escorts . Privateering . The first sort of commerce raiding was for nations to commission privateer s . Early instances of this type of warfare were by the British and Dutch against the Spanish treasure fleet s of the 16th century , which resulted in financial gain for both captain and crew upon capture of enemy vessels ( " prizes " ) . 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 . Napoleonic Wars . During Britain ' s wars against revolutionary and Napoleonic France , the Royal Navy dominated the seas . France adopted a " guerre de course " strategy by licensing civilian privateer s to seize British shipping . British East Indiamen of the time were therefore heavily armed to protect themselves against such raids , at the cost of considerable speed and maneuverability . Some East Indiamen , such as the " Arniston " , were successfully able to fend off these attacks in other parts of the world ; others , such as when " Kent " met " Confiance " in 1800 , were less fortunate . Even in major naval engagements , wooden ships of the line might rarely be destroyed ; for instance , only one warship was sunk at Trafalgar in 1805 . U . S . and British privateers also actively raided each other ' s shipping during the War of 1812 . American Civil War . During the American Civil War , the Confederate Navy operated a fleet of commissioned Confederate States Navy commerce raiders . These differed from privateer s as they were state - owned ships with orders to destroy enemy commerce rather than privately owned ships with letters of marque . These included " Sumter " , " Florida " , " Alabama " , and " Shenandoah " . Most of the ships used in this period were built in Britain , which resulted in the Alabama Claims . Steel navies . By the 1880s , the navies of Europe began to deploy warships made of iron and steel . The natural evolution that followed was the installation of more powerful guns to penetrate the new steel warships . No longer would navies fight for " prizes " , in which capture of the enemy warship meant financial gain for captain and crew as well as government when the prize and her cargo were auction ed . The advent of steel armor and high explosive and armor - piercing shells meant the destruction and sinking of enemy " men o ' war " was the priority . First seen at the Sinope in 1853 , the change was little appreciated until 1905 , when at Tsushima seven pre - dreadnought s were sent to the bottom , and the only prizes were those that had voluntarily surrendered . World War I . World War I saw Germany conducting a commerce war ( " " Handelskrieg " " ) against Britain and her allies , principally with U - boats , but also with merchant raider s and regular warships , and even occasionally with naval airship s . World War II . During World War II , the Battle of the Atlantic saw Germany conducting " guerre de course " against Britain and its allies , again using U - Boat s , auxiliary cruiser s , and small groups of warships ( raiders ) . Limitations set by the Treaty of Versailles meant Germany could not build a large battle fleet as she had in the time leading up to the World War I , and chose to covertly develop her submarines instead . U - boats were cheaper and quicker to build than capital ships , and consequently Germany built up a submarine force rather than a surface fleet . 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 " s , as well as her auxiliary cruisers , also participated in this strategy . In addition , a number of commercial vessels were converted , perhaps the most famous being " Atlantis " . During World War II , elements of the United States Navy based in Brazil conducted operations in the Atlantic against German commerce raiders and blockade runner s . In the Pacific , the U . S . Navy operated against Japanese merchant shipping , as well as engaging in offensive operations against ships of the Japanese Imperial Navy . The bulk of the Japanese merchant marine was sunk by American submarines . By the end of the war , only 12 % of Japan ' s pre - war merchant tonnage was still 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 pressure on the shipping lanes . The Japanese Navy participated in some commerce raiding , but concentrated its efforts toward a " decisive battle " in the Pacific , which never took place .