Hunyadi adopted the Hussite method of using wagons for military purposes. He employed professional soldiers, but also mobilized local peasantry against invaders. These innovations contributed to his earliest successes against the Ottoman troops who were plundering the southern marches in the early 1440s. Although defeated in the battle of Varna in 1444 and in the second battle of Kosovo in 1448, his successful "Long Campaign" across the Balkan Mountains in 1443–44 and defence of Belgrade (Nándorfehérvár) in 1456, against troops led personally by the Sultan established his reputation as a great general. The pope ordered that European Churches ring their bells at noon to gather the faithful in prayer for those who were fighting. The bells of Christian churches are rung at noon to commemorate the Belgrade victory.