The 1st Army was a Royal Yugoslav Army formation commanded by Armijski đeneral Milan Rađenković during the German-led Axis invasion of the Kingdom of Yugoslavia in April 1941 during World War II. It consisted of one infantry division, one horsed cavalry division, and two brigade-strength infantry detachments. It formed part of the 2nd Army Group, and was responsible for the defence of the section of the Yugoslav-Hungarian border between the Danube and the Tisza rivers.

The Yugoslav Army, commonly the Royal Yugoslav Army, was the land warfare military service branch of the Kingdom of Yugoslavia. It existed from the Kingdom's formation in December 1918, until its surrender to the Axis powers on 17 April 1941. Aside from fighting along the Austrian border in 1919 and 1920 related to territorial disputes, and some border skirmishes on its southern borders in the 1920s, the JV was not involved in fighting until April 1941 when it was quickly overcome by the German-led invasion of Yugoslavia.