Tarnovo Constitution
The modern Bulgarian military dates back to 1878. On 22 July 1878 (10 July O.S.) a total of 12 battalions of "opalchentsi" who participated in the Liberation war, formed the Bulgarian armed forces. According to the Tarnovo Constitution, all men between 21 and 40 years of age were eligible for military service. In 1883 the military was reorganised in four infantry brigades (in Sofia, Pleven, Ruse and Shumen) and one cavalry brigade.