 On 26 August 1788 he won distinction in a skirmish at the Törzburger Pass at the head of a hussar squadron.Gyulay transferred into his father's regiment as a Hauptmann (captain) of grenadiers in February 1789 and fought at the Siege of Belgrade in autumn that year.He led his company in the "Kempf" grenadier battalion in Franz von Werneck's column during the successful assault on the city, which capitulated on 8 October.