The Ottoman–Habsburg wars refers to the military conflicts between the Ottoman Empire and the Habsburg dynasties of the Austrian Empire, Habsburg Spain and in certain times, the Holy Roman Empire and the Kingdom of Hungary. The war would be dominated by land campaigns in Hungary and present day Croatia. Initially, Ottoman conquests in Europe made significant gains with a decisive victory at Mohács reducing around one third (central) part of Kingdom of Hungary to the status of an Ottoman tributary.
By the 16th century, the Ottomans had become a serious threat to Europe, with Ottoman Barbary ships sweeping away Venetian possessions in the Aegean and Ionia. The Protestant Reformation, the France-Habsburg rivalry and the numerous civil conflicts of the Holy Roman Empire served as distractions. Meanwhile the Ottomans had to contend with the Persian Safavid Empire and to a lesser extent the Mamluke Sultanate, which was defeated and fully incorporated into the empire.
Later, the Peace of Westphalia and the Spanish War of Succession in the 17th and 18th centuries respectively left the Austrian Empire as the sole firm possession of the House of Habsburg. By then, however, European advances in guns and military tactics outweighed the skill and resources of the Ottomans and their elite Janissaries, enabling the Habsburgs to retake Hungary. The Great Turkish War ended with three decisive Holy League victories at Vienna, Mohács and Zenta. The wars came to an end when the Austrian Empire and the Ottoman Empire signed an alliance with the German Empire prior to World War I. Following their defeat in that war, both Empires were dissolved and both Houses continue to claim the title of Caesar.