sentences:  Due to the lack of payment, some of the Black Army mercenaries, mostly Czechs, switched sides and joined the Holy Roman army of 20,000 men in invading Hungary.They advanced in the heart of Hungary and managed to capture the city of Székesfehérvár, which he sacked, as well as the tomb of King Matthias, which was kept there.His Landsknechts were still unsatisfied with the plunder and refused to go for taking Buda.