After training at the artillery cadet school in Traiskirchen and Theresia Military Academy, Feketehalmy-Czeydner became a lieutenant in 1910 for Zeidner Feldhaubitzregiment No.

After the war, he joined the newly founded Royal Hungarian Army, where he served in 1921 as a staff officer at the 7th Mixed Brigade in Miskolc.

Three battalions under Colonel László Deák were dispatched to the area where they received assistance from local police, gendarmerie and army units that were home.

[1] The Novi Sad massacre sparked protests in Hungary, which were led by the chairman of the opposition Smallholders Party, Endre Bajcsy-Zsilinszky.

As recently as September 1943, when Hungary was already in negotiations with Western powers over a separate peace, a case was brought against the officers responsible.

After the coup of Hitler faithful by the Arrow Cross party under Ferenc Szálasi he went back to Hungary in October 1944 and became Deputy Minister of Defence.