The Battle of Bucharest, also known as the Argeş–Neajlov Defensive Operation in Romania, was the last battle of the Romanian Campaign of 1916 in World War I, in which the Central Powers' combatants, led by General Erich von Falkenhayn, occupied the Romanian capital and forced the Romanian Government, as well as the remnants of the Romanian Army to retreat to Moldavia and re-establish its capital at Iaşi. The battle was of defensive nature, as the Romanian Army was joined by a part of the Imperial Russian army. The Romanian Army, led by General Constantin Prezan, had previously been unable to stop the German counterattack in Muntenia. The armed forces that made up the German counterattack were mostly German, two armed groups attacking concentrically, one from the direction of Oltenia and the other from the south of the Danube. The sheer number of troops involved, as well as the large area of operations, make it one of the most complex battles fought on Romanian soil during the war. The battle took place between 13 and 16 December 1916. At the same time, between 14 and 19 December 1916, the battle of Argeș took place. There, the Bulgarian and German armies led by General August von Mackensen reported a glorious victory. The outcome of the two battles was Bucharest being occupied on 19 December by the Central Powers and the Romanian and Russian forces' retreat to Moldavia, all the way to the Siret. On 27 November 1916, three main events took place which enabled the Central Powers to commence the offensive towards Bucharest: following a successful holding action at Slatina, the Romanians abandoned the line of the Olt River, the German 9th Army and Mackensen's Danube Army had linked up, and the Danube had been secured by the Bulgarian capture of Giurgiu. The Romanian and Russian forces, made up of approximately 150.000 men, were led by General Constantin Prezan, while the Central Powers' armed forces were led by General August von Mackensen and Erich von Falkenhayn.