her mother, Elizabeth of Bosnia, who had acted as regent, in 1387 by the rebellious House of Horvat, Bishop Paul Horvat of Mačva, his brother John Horvat and younger brother Ladislav. Sigismund's mother-in-law was strangled, while Mary was liberated. Having secured the support of the nobility, Sigismund was crowned King of Hungary at Székesfehérvár on 31 March 1387. Having raised money by pledging Brandenburg to his cousin Jobst, Margrave of Moravia (1388), he was engaged for the next nine years in a ceaseless struggle for the possession of this unstable throne. The central power was finally weakened to such an extent that only Sigismund's alliance with the powerful Czillei-Garai League could ensure his position on the throne. It was not for entirely selfless reasons that one of the leagues of barons helped him to power: Sigismund had to pay for the support of the lords by transferring a sizeable part of the royal properties. (For some years, the baron's council governed the country in the name of the Holy Crown). The restoration of the authority of the central administration took decades of work. The bulk of the nation headed by the House of Garai was with him; but in the southern provinces between the Sava and the Drava, the Horvathys with the support of King Tvrtko I of Bosnia, Mary's maternal uncle, proclaimed as their king Ladislaus of Naples, son of the murdered Charles II of Hungary. Not until 1395 did Nicholas II Garai succeed in suppressing them. Mary died heavily pregnant in 1395. To ease the pressure from Hungarian nobles, Sigismund tried to employ foreign advisors, which was not popular, and he had to promise not to give land and nominations to anyone other than Hungarian nobles. However, this was not applied to Stibor of Stiboricz, who was Sigismund's closest friend and advisor. On a number of occasions, Sigismund was imprisoned by nobles, but with the help of the armies of Garai and Stibor of Stiboricz, he was able to regain power. Crusade of Nicopolis In 1396, Sigismund led the combined armies of Christendom against the Turks, who had taken advantage of the temporary helplessness of Hungary to extend their dominion to the banks of the Danube. This crusade, preached by Pope Boniface IX, was very popular in Hungary. The nobles flocked in their thousands to the royal standard, and were reinforced by volunteers from nearly every part of