On 6 September, he was appointed by Regent Miklós Horthy to succeed the pro-German Henrik Werth as Chief of General Staff.

[citation needed] He successfully delayed this measure until it could no longer be avoided following German Army setbacks in the winter of 1941-42 and the increased commitment of Romania.

Previously, in response to alleged attacks by communist partisans and Chetniks in the annexed Bácska, he ordered a military intervention by General Ferenc Feketehalmy-Czeydner, which evolved into punitive action against Serb-inhabited villages and culminated in the massacre of Újvidék (present-day Novi Sad).

Szombathelyi's proposal to use Hungarian divisions to occupy the Balkans as a substitute for the failure of the second Army was welcomed by Hitler but rejected by Prime Minister Miklós Kállay.

Hungarian writer Tibor Cseres in his book "Vengeance in Bácska" states that Szombathelyi was impaled, but there is no conclusive evidence of this.