Romania in World War I

Romania in World War I
Part of the Eastern Front of World War I
Romanian troops at Mărășești battlefield in 1917.
Date 1st phase: 27 August 1916–December 1917 2nd phase: 10–11 November 1918 Location Romania Result Central Powers victory (December 1917) Armistice of Focșani Treaty of Bucharest Allied victory (November 1918) Treaties of Versailles, Saint-Germain, Neuilly, and Trianon
Belligerents
Germany  Austria-Hungary  Bulgaria  Ottoman Empire	Romania Russian Empire (until 1917)  Russian Republic (1917)  Serbia[1] Supported by:  France
Commanders and leaders
Erich von Falkenhayn August von Mackensen Johannes von Eben Archduke Karl A. A. von Straußenburg Franz Rohr von Denta Stefan Toshev Mustafa Hilmi Pasha	Ferdinand I Constantin Prezan Alexandru Averescu Eremia Grigorescu Ioan Culcer Mihail Aslan Vladimir Sakharov Dmitry Shcherbachev Andrei Zayonchkovski Milenko Milićević Henri Berthelot
Units involved
9th Army Danube Army 1st Army 3rd Army VI Corps Danube Flotilla Constantinople Flotilla	Romanian Front 4th Army Danube/6th Army 9th Army 2nd Army 1st Army 8th Army 4th Army 3rd Army Dobruja Army 1st Serbian Division French Mission Romanian Navy
Strength
750,000[2] 143,049 (1916)[3] 20,000 (1916)[4] 39,000 (1917)[5]	1916:[6] 658,088 30,000 20,000 1,600 1917: 400,000 1,000,000 Romanian Corps: 1,000+
Casualties and losses
191,000[7][8] 96,600[9][10] 30,250+[11][12][13] 20,000[14] 1 river monitor sunk 1 river monitor disabled 1 submarine sunk 1 aircraft destroyed Total: 338,000 casualties	535,700[15] 335,706 dead 120,000 wounded 80,000 captured 50,000 Romanian Corps: 500 9,000 3,000 dead 6,000 wounded 2 torpedo boats sunk 1 gunboat sunk Total: 595,000 casualties
330,000–430,000 Romanian civilians dead from war-related causes between 1914 and 1918[16]

The Kingdom of Romania was neutral for the first two years of World War I, entering on the side of the Allied powers from 27 August 1916 until Central Power occupation led to the Treaty of Bucharest in May 1918, before reentering the war on 10 November 1918. It had the most significant oil fields in Europe, and Germany eagerly bought its petroleum, as well as food exports.

From the point of view of its belligerent status, Romania was a neutral country between 28 July 1914 and 27 August 1916, a belligerent country on the part of the Entente from 27 August 1916 to 9 December 1917, in a state of armistice with the Central Powers from 10 December 1917 to 7 May 1918, a non-combatant country between 7 May 1918 and 10 November 1918, and finally a belligerent country in the Entente between 10 and 11 November 1918.

At the start of World War I, King Carol I of Romania favored Germany, while the nation's political elite favored the Entente. As such, the crown council decided to remain neutral. But after King Carol's death in 1914, his successor King Ferdinand I favored the Entente. For Romania, the highest priority was taking Transylvania from Hungary, with around 2,800,000 Romanians out of around 5,000,000 people. The Allies wanted Romania to join their side in order to cut rail communications between Germany and Turkey, and to cut off Germany's oil supplies. Britain made loans, France sent a military training mission, and Russia promised modern munitions. The Allies promised at least 200,000 soldiers to defend Romania against Bulgaria to the south, and help it invade Austria-Hungary.

At the outbreak of hostilities, the Austro-Hungarian Empire invoked a casus foederis on Romania and Italy linked to the secret treaty of alliance since 1883. However, both Italy and Romania refused to honor the treaty on the grounds that it was not a case of casus foederis because the attacks on Austria were not "unprovoked", as stipulated in the treaty of alliance. In August 1916, Romania received an ultimatum to decide whether to join the Entente "now or never". Under the pressure of the ultimatum, the Romanian government agreed to enter the war on the side of the Entente, although the situation on the battle fronts was not favorable.

The Romanian campaign was part of the Eastern Front of World War I, with Romania and Russia allied with Britain and France against the Central Powers of Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria. Fighting took place from August 1916 to December 1917 across most of present-day Romania, including Transylvania, which was part of the Austro-Hungarian Empire at the time, as well as in Southern Dobruja, which is currently part of Bulgaria.

The Romanian campaign plan (Hypothesis Z) consisted in attacking Austria-Hungary in Transylvania, while defending Southern Dobruja and Giurgiu from Bulgaria in the south. Despite initial successes in Transylvania, after German divisions started aiding Austria-Hungary and Bulgaria, the Romanian forces (aided by Russia) suffered massive setbacks, and by the end of 1916 out of the territory of the Romanian Old Kingdom only Western Moldavia remained under the control of the Romanian and Russian armies.

After several defensive victories in 1917 at Mărăști, Mărășești, and Oituz, with Russia's withdrawal from the war following the October Revolution, Romania, almost completely surrounded by the Central Powers, was also forced to drop out of the war. It signed the Treaty of Bucharest with the Central Powers in May 1918. Under the terms of the treaty, Romania would lose all of Dobruja to Bulgaria, all the Carpathian passes to Austria-Hungary and would lease all of its oil reserves to Germany for 99 years. However, the Central Powers recognized Romania's union with Bessarabia who had recently declared independence from the Russian Empire following the October Revolution and voted for union with Romania in April 1918. The parliament signed the treaty, but King Ferdinand refused to sign it, hoping for an Allied victory on the western front. In October 1918, Romania renounced the Treaty of Bucharest and on 10 November 1918, one day before the German armistice, Romania re-entered the war after the successful Allied advances on the Macedonian front and advanced in Transylvania. The next day, the Treaty of Bucharest was nullified by the terms of the Armistice of Compiègne.