Romania’s unwise decision to join the Allies now sees its armies engaged in a desperate battle for national survival. German, Austro-Hungarian and Bulgarian troops have invaded the country, with Mackensen leading one force attacking along the coast while Falkenhayn pushes into Romania from the Carpathians. German and Austro-Hungarian forces have also pushed into Moldavia, but here they have been checked by Russian forces. However the Russians do not have enough men to spare for the defence of the rest of Romania. Allied diversionary attacks in Macedonia have also done little to help the Romanians.
Now the fighting enters a new phase. Mackensen moves some of his men to the west, where they make a surprise crossing of the Danube at Sistova. Mackensen’s plan is for this Danube Army to march on Bucharest and bring Romanian resistance to an end.
But the battle for Romania is not over yet. Romanian commanders note that Falkenhayn and Mackensen’s armies are still widely separated from each other. They plan a desperate counter-attack, hoping that if they commit their reserves against one of the enemy armies they might be able to destroy it and then turn on the other. Even if they are unable to achieve a Romanian Tannenberg, they may be able to buy time for Russian reinforcements to arrive. So the Romanians begin their preparations for a last desperate offensive against Mackensen’s Danube army.