The Battle of Șelimbăr, or Battle of Sellenberk (; ), took place on 18 October 1599 between the Romanian army of Michael the Brave () and the Transylvanian-Hungarian army of Andrew Báthory (). The battle was fought near the village of Șelimbăr () close to Sibiu (; ). Background Michael the Brave marched into Transylvania to fight against the Ottomans. The neighboring rulers Andrew Báthory in Transylvania and Ieremia Movilă in Moldavia were friendly towards Poland. In 1598, Michael signed a treaty of peace with the Ottomans, however both sides knew that the issue was far from settled. When Transylvania fell under the influence of Poland, which preserved friendly relations with the Ottomans, a hostile ring closed around Wallachia. Only the Habsburgs were prepared to ally themselves with Michael. The treaty, signed in Prague on 9 June 1598, made Wallachia a vassal state; in exchange, the emperor undertook to cover the cost of providing 5.000 mercenaries to the principality. The voivode wanted to secure a land link to his ally. With Emperor Rudolph's assent, he launched an attack on Transylvania. He informed the Székelys that he was attacking Transylvania on behalf of the Emperor Rudolf and, if they join him, their traditional freedoms will be restored. At this the Székelys joined the forces of Michael en masse so that Székelys comprised one third of his army of 36,000 soldiers. Michael entered Transylvania through Buzău Pass. Another Wallachian army corp, composed of 6,000 warriors from Oltenia, led by Radu Buzescu Ban Udrea and serbian hajduk commander Baba Novak, crossed the Transylvanian Alps through Turnu Roşu Pass. The junction was made on October 16. The battle Michael had approximately 40,000 men at his command. Many of them did not fight, however, preferring instead to remain in the camp and protect the women and children of the boyars who had joined them in this campaign out of the fear of possible Tatar attacks in Wallachia. The army of Andrew Báthory numbered approximately 30,000 men, but during the battle many defected to Michael's army, including the Székelys, who despised the ruling Báthory family. The Wallachians gained the upper hand at the beginning of the battle, but were pushed back quickly by the charge of the Hungarian Hussars. The Transylvanians then had the opportunity to win the battle, but Andrew Báthory refused to commit his rearguard to battle, giving the Wallachians a chance to regroup.