 Formed after World War I, the Royal Yugoslav Army was still largely equipped with weapons and material from that era, although some modernization with Czech equipment and vehicles had begun.Of about 4,000 artillery pieces, many were aged and horse-drawn, but about 1,700 were relatively modern, including 812 Czech 37mm and 47mm anti-tank guns.There were also about 2,300 mortars, including 1,600 modern pieces, as well as twenty-four and pieces.