There are differing accounts on his origin. He has been described as: a Banat Swabian ; an ethnic Serb, born in Ruma, Austria-Hungary, who adopted the surname Kirchner from his stepfather who adopted and raised him; an ethnic Serb, born in Klein-Betschkerek, Austria-Hungary, who adopted the surname from his stepfather, whom his mother remarried. Ruma was a town which had a Serb majority and minorities of Germans, Hungarians and Croats, while Klein-Betschkerek was a village which had a German majority and minorities of Serbs and Romanians. He grew up speaking German, and only learnt Serbian while serving in the Austro-Hungarian army.
Austro-Hungarian service
Kirhner finished the Military Academy in Vienna, then served in the Austro-Hungarian army as an officer in Vinkovci in the Kingdom of Croatia-Slavonia for seven years. Here, he learnt Serbian; it is said that he learnt to speak fluently, but with a likable German accent. He deserted from the Austro-Hungarian army in 1914 and crossed into the Kingdom of Serbia. According to unconfirmed stories of his comrades, he had deserted after killing a superior officer who, knowing of Kirhner's ancestry or not, had talked very insulting and degrading about Serbs.
World War I
Kirhner joined the Serbian Army, being accepted by decree by King Peter I of Serbia. According to unreliable stories, Kirhner fled to Serbia swimming across the Sava river to Belgrade in the summer of 1914, and was the first to bring news that the Austro-Hungarian government was ready to declare war regardless of the response to the July Ultimatum. Kirhner began his service in the World War I campaign as a Chetnik volunteer. In 1914 he participated in the capture of an Austro-Hungarian military post on the left shore of the Sava, during which he was wounded in the right foot, but declined to go to hospital. He gathered youngsters from Syrmia and Banat who had managed to escape to Belgrade and wanted to join the Serbian Army, but as they were too young, they joined as volunteers. At first, his volunteer unit numbered 15, but quickly rose up to 400. During the defense of Belgrade in fall 1915, Kirhner commanded the Srem Volunteer Detachment. In late September, when the state in Belgrade was critical, he led his unit which defended the railway embankment from the "Zlatni šaran" kafana to Knez MihailovaVenac from the incoming Austro-Hungarians. The volunteers suffered great losses. The detachment participated in the assault led by major Dragutin Gavrilović on 7 October. Kirhner was seriously wounded in the same foot, and was saved by his comrades who took him away from the first line of defense. The command of the detachment was taken over by Živko J. Kezić. The detachment was ordered to retreat to the heights south of Belgrade, which was the beginning of the large and organized departure of the army towards southern Serbia, Kosovo, Montenegro and Albania. Kirhner was treated in Niš, and was with other wounded transferred to Corfu. His nurse was Bosiljka "Bosa" Čajkanović, the sister of reserve captain Veselin Čajkanović, the later academic. During the retreat to Corfu, Kirhner and Bosiljka fell in love, and they later married. From Corfu, he was sent to treatment in Toulouse. There he was healed, but his two woundings in the same foot left him disabled with a 6 cm shorter foot. He finished electro-technical faculty in France. He was described as a 'great Serbian patriot'. As a Chetnik commander, he received the title of vojvoda.
Interwar period
After the war, he held high offices in the Military-Technical and Engineering Department of the Army and Navy. He married Bosiljka, his war-time love. In the Yugoslav Army, Ignjat Kirhner had the rank of an engineering technical lieutenant, then rose to the rank of brigadier-general. For a period of time, he was the President of the "Association of Belgrade Defenders 1914–1915".
