The Romanian government asserted that the moment was right for it to fulfill the country's national ambitions by aligning itself with the Entente, and declared war on the Austro-Hungarian Empire on 27 August 1916.

In a short time the Romanian forces occupied Orșova, Petroșani, and Brașov, and reached Sibiu on their way to the river Mureș, the main objective of the offensive.

Simultaneously with the assault of the fortress of Turtucaia, the Bulgarian Third Army defeated the Romanian-Russian force, including the First Serbian Volunteer Division, at the Battle of Bazargic, despite their numerical superiority.

[1] The outnumbered forces of the Central Powers managed to push the Romanians and the Russians north, while the Serbian Volunteer division suffered heavy casualties with 8,539 dead and wounded.

The battle ended in Entente tactical victory and forced the Central Powers to hold their offensive and assume a defensive stance till the middle of October.