an exceptional naval commander in the form of Khair ad Din, known to Europeans as Barbarossa. Once appointed admiral-in-chief, Barbarossa was charged with rebuilding the Ottoman fleet. In 1535, Charles V led a Holy League of 26,700 soldiers (10,000 Spaniards, 8,000 Italians, 8,000 Germans, and 700 Knights of St. John) to victory against the Ottomans at Tunis, which together with the war against Venice the following year, led Suleiman to accept proposals from Francis I of France to form an alliance against Charles. Huge Muslim territories in North Africa were annexed. The piracy carried on thereafter by the Barbary pirates of North Africa can be seen in the context of the wars against Spain. In 1541, the Spaniards led an unsuccessful expedition to Algiers. In 1542, facing a common Habsburg enemy during the Italian Wars, Francis I sought to renew the Franco-Ottoman alliance. In early 1542, Polin successfully negotiated the details of the alliance, with the Ottoman Empire promising to send 60,000 troops against the territories of the German king Ferdinand, as well as 150 galleys against Charles, while France promised to attack Flanders, harass the coasts of Spain with a naval force, and send 40 galleys to assist the Turks for operations in the Levant. In August 1551, Ottoman naval commander Turgut Reis attacked and captured Tripoli which had been a possession of the Knights of Malta since 1530. In 1553, Turgut Reis was nominated commander of Tripoli by Suleiman, making the city an important center for piratical raids in the Mediterranean and the capital of the Ottoman province of Tripolitania. In 1560, a powerful naval force was sent to recapture Tripoli, but that force was defeated in the Battle of Djerba. Elsewhere in the Mediterranean, when the Knights Hospitallers were re-established as the Knights of Malta in 1530, their actions against Muslim navies quickly drew the ire of the Ottomans, who assembled another massive army in order to dislodge the Knights from Malta. The Ottomans invaded Malta in 1565, undertaking the Great Siege of Malta, which began on 18 May and lasted until 8 September, and is portrayed vividly in the frescoes of Matteo Perez d'Aleccio in the Hall of St. Michael and St. George. At first, it seemed that this would be a repeat of the battle on Rhodes, with most of Malta's cities destroyed and half the Knights killed in battle; but a relief force from