1916 battle of World War I
The Dobruja Campaign was a major operation during the Romanian Campaign of World War I. It took place between 2 September and 25 October 1916 between a joint Bulgarian–German–Ottoman force, consisting mainly of the Bulgarian Third Army, and a Romanian–Russian force. The battle was part of the Romanian campaign towards the end of 1916. It ended with a Central Powers victory.
Background.
By August 1916 the Central Powers found themselves in an increasingly difficult military situation – in the West the German offensive at Verdun had turned into a costly battle of attrition, in the East the Brusilov Offensive was crippling the Austro-Hungarian Army, and in the South the Italian Army was increasing the pressure on the Austro-Hungarians, while General Maurice Sarrail's Allied expeditionary force in northern Greece seemed poised for a major offensive against the Bulgarian Army.
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. Three Romanian armies invaded Transylvania through the Carpathian Mountains, pushing back the much smaller Austro-Hungarian First Army. 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.
In response the German Empire declared war on the Kingdom of Romania on 27 August, with the Kingdom of Bulgaria following suit on 1 September. On the next day the Bulgarian Third Army initiated the Central Powers' first major offensive of the campaign by invading Southern Dobruja.
Battle.
Turtucaia.
The Battle of Turtucaia was very important due to its consequences. As for the southern front (on the Romanian–Bulgarian border), it allowed the Bulgarian-German troops to attack Dobrogea (which they later occupied). Much more serious was the fact that on the northern front (from Transylvania) the offensive carried out by the Romanian troops against the German and Austro-Hungarian troops was stopped, seven divisions being taken from this sector and transferred to the southern front. Even if later six of them returned to the northern front, the halting of the offensive in Transylvania allowed, on the one hand, the concentration of German and Austro-Hungarian troops, which were able to launch an offensive that resulted in pushing the Romanian troops to the Carpathian line, and, on the other hand, later allowed the invasion of Muntenia.
Bazargic.
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. 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. 
On 7 September after intense fighting the defeated Russian general ordered a withdrawal.
Cobadin I.
The First Battle of Cobadin was a battle fought from 17 to 19 of September 1916 between the Bulgarian Third Army and the Romanian–Russian Army of the Dobruja. 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.
The right flank of the Allied forces was supported by the Romanian Navy's Danube Flotilla, consisting mainly of four "Brătianu"-class river monitors. These warships blocked with mines the river sectors of Silistra, Ostrov, and Gura Borcea, protected the 8 September evacuation of Silistra, attacked enemy land convoys, and destroyed enemy batteries.
Cobadin II.
The Second Battle of Cobadin was a battle fought from 19 to 25 October 1916 between the Central Powers, chiefly the Bulgarian Third Army, and the Entente, represented by the Russo–Romanian Dobruja Army. The battle ended in a decisive victory for the Central Powers; it resulted in the occupation of the strategic port of Constanța and the capture of the railway between that city and Cernavodă.
Aftermath.
Despite the loss of most of Dobruja to the Central Powers, the Romanian defensive victory at Tulcea in January 1917, combined with the actions of the Romanian cruiser "Elisabeta" at the mouths of the Danube, ensured Romanian control over the entire Danube Delta throughout the rest of the War.
References.
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