The Ottoman military's regularized use of firearms proceeded ahead of the pace of their European counterparts. The Janissaries had initially been an infantry bodyguard using bows and arrows. By the time of Sultan Mehmed II, they had been drilled with firearms and became "perhaps the first standing infantry force equipped with firearms in the world." The Janissaries are thus considered the first modern standing armies. The combination of artillery and Janissary firepower proved decisive at Varna in 1444 against a force of Crusaders, and later Başkent in 1473 against the Aq Qoyunlu.