By the end of Suleiman's reign, the Empire spanned approximately , extending over three continents. In addition, the Empire became a dominant naval force, controlling much of the Mediterranean Sea. By this time, the Ottoman Empire was a major part of the European political sphere. The Ottomans became involved in multi-continental religious wars when Spain and Portugal were united under the Iberian Union, the Ottomans as holders of the Caliph title, meaning leader of all Muslims worldwide, and Iberians, as leaders of the Christian crusaders, were locked in a worldwide conflict, with zones of operations in the Mediterranean Sea and Indian Ocean where Iberians circumnavigated Africa to reach India, and on their way, wage wars upon the Ottomans and their local Muslim allies. Likewise, the Iberians passed through newly-Christianized Latin America and had sent expeditions that traversed the Pacific in order to Christianize the formerly Muslim Philippines and use it as a base to further attack the Muslims in the Far East. In this case, the Ottomans sent armies to aid its easternmost vassal and territory, the Sultanate of Aceh in Southeast Asia. During the 1600s the worldwide conflict between the Ottoman Caliphate and Iberian Union was a stalemate since both powers were at similar population, technology and economic levels. Nevertheless, the success of the Ottoman political and military establishment was compared to the Roman Empire, by the likes of the contemporary Italian scholar Francesco Sansovino and the French political philosopher Jean Bodin.