The conquests of Nice (1543) and Corsica (1553) occurred on behalf of France as a joint venture between the forces of the French king Francis I and the Ottoman sultan Suleiman I, and were commanded by the Ottoman admirals Barbarossa Hayreddin Pasha and Turgut Reis. A month prior to the siege of Nice, France supported the Ottomans with an artillery unit during the Ottoman conquest of Esztergom in 1543. France and the Ottoman Empire, united by mutual opposition to Habsburg rule in both Southern and Central Europe, became strong allies during this period. The alliance was economic and military, as the sultans granted France the right of trade within the Empire without levy of taxation. By this time, the Ottoman Empire was a significant and accepted part of the European political sphere. It made a military alliance with France, the Kingdom of England and the Dutch Republic against Habsburg Spain, Italy and Habsburg Austria.