The princes of Transylvania, Wallachia, and Moldavia joined the Holy League against the Ottoman Empire in 1594. The Wallachian prince, Michael the Brave, united the three principalities under his rule in May 1600. The neighboring powers forced him to abdicate in September, but he became a symbol of the unification of the Romanian lands in the 19th century. Although the rulers of the three principalities continued to pay tribute to the Ottomans, the most talented princes—Gabriel Bethlen of Transylvania, Matei Basarab of Wallachia, and Vasile Lupu of Moldavia—strengthened their autonomy.