The Ottoman Empire often interfered in the affairs of Transylvania, always an unruly district, and this interference brought on a war with the Holy Roman Empire, which after some desultory operations really began in 1663. By a personal appeal to the diet at Regensburg Leopold induced the princes to send assistance for the campaign; troops were also sent by France, and in August 1664, the great Imperial general Raimondo Montecuccoli gained a notable victory at Saint Gotthard. By the Peace of Vasvár the Emperor made a twenty years' truce with the Sultan, granting more generous terms than his recent victory seemed to render necessary.