The aim of this thesis is to show how disciplined and well-trained the army of Matthias Corvinus was which is typical of mercenaries. Matthias I relieved nobility of military service and appointed mercenaries financially dependent on the King. Combined with Matthias' organizational skills, this army way able to resist an enemy who outnumbered them. The goal of describing Matthias' army is also to show how high the price of this kind of army was and that only a highly capable statesman and army leader such as Matthias Corvinus would be able to maintain it. The army was influenced by geopolitical and financial factors of the time, but under the commend of a capable leader, it managed to generate a much larger success than other armies of western Europe where the military development was directed towards the creation of standing armies. However, Matthias' efforts in creating a standing army should not be disregarded. To conclude, with this kind of army, Matthias managed to occupy big and wealthy territories north and west of Kingdom of Hungary, but after a long period of military activity of the Black Army, the country's resources were exhausted. After Matthias' death, the Black Army itself slowly disappeared.