The naval history of the Netherlands dates back to the 15th century. As overseas trade was a traditional cornerstone of the Dutch economy, naval defence was indispensable for the protection of commercial interests. Origins At first the Dutch navy had a private character. Wealthy merchants and local authorities in the many ports of the Low Countries took initiative to arm ships since the 15th century and incidentally attacked pirates and foreign competitors. Defensive measures to protect the merchant ships could include sailing in a convoy and arming the merchants themselves. Offensive actions could include taking enemy ships by force. This was actively supported by the Dutch authorities in times of war, who handed out letters of marque, allowing Dutch captains to attack and, if possible capture enemy ships and their cargoes. The central authorities tried, in vain, to increase supervision on these private navies. By decree of Maximilian of Austria, on 8 January 1488 the forerunner of the Dutch Navy was formed. The role of the navy had a legal status from then on, and the task of defending the country at sea was the responsibility of the Admiral of Flanders, later Admiral of the Netherlands, appointed by the sovereign. However, many provinces surreptitiously created small navies of their own, without informing the admiral. A world power The Dutch revolt (1568–1648) in many ways started with the revolt of the Beggars and the navy was no exception. William the Silent, the leader of the revolt, issued letters of marque under his authority as sovereign Prince of Orange. These roving bands of ships became known as the Sea Beggars. Their capture of Brielle was the first significant victory of the revolt, and led to the entire province of Holland and Zealand declaring for the Prince and against the Habsburg overlord, Philip II of Spain and the Spanish government. As the revolt progressed into an independent government and state, the navy was reorganized into a better command structure. The government of the newly established Dutch Republic installed five admiralties (de Maze, Amsterdam, Zeeland, the Noorderkwartier, and Friesland) which had offices in Rotterdam, Amsterdam, Middelburg, Hoorn, Enkhuizen, and Dokkum (later Harlingen). During the 17th century the Dutch Republic was involved in many wars, many of them at sea. The main goal of the Dutch navy was to protect shipping lanes all over the world and, if need be, to repel a naval invasion