The first sort of commerce raiding was for nations to commission privateers. Early instances of this type of warfare were by the British and Dutch against the Spanish treasure fleets 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.
17th and 18th centuries
Privateers formed a large part of the total military force at sea during the 17th and 18th centuries. In the First Anglo-Dutch War, English privateers attacked the trade on which the United Provinces entirely depended, capturing over 1,000 Dutch merchant ships. During the subsequent war with Spain, Spanish and Flemish privateers in the service of the Spanish Crown, including the notorious Dunkirkers, captured 1,500 English merchant ships, helping to restore Dutch international trade. Dutch privateers and others also attacked British trade, whether coastal, Atlantic, or Mediterranean, in the Second and Third Anglo-Dutch wars.
During the Nine Years War, French policy strongly encouraged privateers, including the famous Jean Bart, to attack English and Dutch shipping. England lost roughly 4,000 merchant ships during the war. In the following War of Spanish Succession, privateer attacks continued, Britain losing 3,250 merchant ships. Parliament passed an updated
Cruisers and Convoys Act in 1708, allocating regular warships to the defence of trade.
In the War of Austrian Succession, the Royal Navy was able to concentrate more on defending British ships. Britain lost 3,238 merchantmen, a smaller fraction of her merchant marine than the enemy losses of 3,434. While French losses were proportionally severe, the smaller but better-protected Spanish trade suffered the least, and Spanish privateers enjoyed much of the best allied plunder of British trade, particularly in the West Indies.