At the onset of the Romanian Campaign of World War I, Praporgescu was named commander of the 20th Infantry Division, which was part of the Romanian 1st Army, under the command of General Ioan Culcer. The campaign started on 27 August 1916 with the Battle of Transylvania. After the Romanian forces launched an offensive towards Sibiu and defeated the defending Austro-Hungarian troops, a counter-offensive was launched by the 9th German Army under the command of Erich von Falkenhayn. From 26–29 September Praporgescu's troops, including those of the 23rd Division under the command of Colonel Traian Moșoiu, fought tenaciously in the Olt and Topolog valleys, blocking an attempted breakthrough by the Bavarian Alpenkorps.