On 27 August 1916, the Kingdom of Romania declared war on Austria-Hungary and proceeded to invade the Hungarian region of Transylvania. The Romanian campaign plan called for the Olt-Lotru Group of the Romanian 1st Army under the command of General Ioan Culcer to secure the basin between Nagytalmács (Tălmaciu/Talmesch) and Nagyszeben (Sibiu/Hermannstadt). The area between Nagyszeben and the northern exit of the Turnu Roșu Pass was the designated assembly area for the 1st Army's Olt-Lotru Group. Opposing the Romanian invasion of Transylvania was the Austro-Hungarian 1st Army, led by General Arthur Arz von Straussenburg.