Before the First Balkan War in 1912, he was in Switzerland being treated for tuberculosis. As soon as the war broke out, he came back to Serbia. There he collected a group of 100 volunteers and entered the Chetnik detachment of Vojin Popović, better known as Voivode Vuk. In the Battle of Kumanovo Dragomir gained a reputation for fearless-bravery under fire. He often took impossible missions with scant regard for his own life; his men felt tremendous confidence in his presence, inspired by his personal courage. In one of the battles he was heavily wounded, and his poor health began to worsen. He died in 1913 in the liberated town of Ohrid. His post as chemistry assistant professor at the university remained vacant during the period he served his country.