Romania is engaged in a desperate battle for national survival in the face of invading German, Bulgarian and Austro-Hungarian armies. Mackensen leads a mainly Bulgarian force from the south while Falkenhayn commands an invasion force advancing from Transylvania in the west.
The Romanians have concentrated their forces and launched counter-attack on Mackensen’s force, hoping to smash his army before Falkenhayn can come to his aid. In some respects they are trying to emulate the 1914 German victories at Tannenberg and the Masurian Lakes, where widely separated Russian armies were defeated in detail.
The battle started well for the Romanians. Mackensen was pushed back and many prisoners taken. But Mackensen and Falkenhayn are not incompetents like Samsonov and Rennenkampf, the unfortunate Russians defeated in 1914. Mackensen quickly recovers from the initial shock and mounts a spirited defence, aided by a contingent of Turkish reinforcements. Falkenhayn meanwhile launches attacks all along his front to aid his colleague.
The Romanian counter-offensive collapses. Flung back in all sectors, the Romanians now retreat to avoid encirclement. The gates of Bucharest lie open for the enemy.
August von Mackensen (The First World War in 261 weeks)