Romania in World War I
The Kingdom of Romania remained neutral throughout the first two years of World War I. They eventually entered the conflict on the side of the Entente from 27 August 1916 until insurmountable pressure from Central Powers - which had occupied two thirds of the country - led to an armistice being signed on 9 December 1917. Six months later, a crippling peace treaty was imposed on Romania, which the government ratified. King Ferdinand I refused to promulgate the treaty, hoping for an Allied victory on the Western Front. As the Central Power war efforts collapsed, Romania re-entered the war on 10 November 1918.
Romania was still a burgeoning state with great territorial ambitions at the onset of the war. It had achieved its independence following the Russo-Turkish War of 1877–1878, although millions of ethnic Romanians continued to reside outside the new nation's borders, particularly in Transylvania and Bessarabia, which were part of Austria-Hungary and Russia respectively. The Romanian monarchy, which was formed by members of the Hohenzollern dynasty, who were of Germanic origin, was sympathetic towards the cause of the Central Powers. The nation's political elite and the majority of the public favoured the Entente, as joining them would allow Romania to take Transylvania from Austria-Hungary, a region rich with natural resources and inhabited by a Romanian majority. Because of this social division and the general feeling that Romania still wasn't fully prepared for a war against a great power, the Romanians initially opted for neutrality.
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 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 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.
Before the war
The Kingdom of Romania was ruled by kings of the House of Hohenzollern from 1866. In 1883, the King of Romania, Carol I of Hohenzollern, signed a secret treaty with the Triple Alliance that stipulated Romania's obligation to go to war only if Austria-Hungary was attacked. While Carol wanted to enter World War I as an ally of the Central Powers, the Romanian public and the political parties were in favor of joining the Triple Entente.Romania remained neutral when the war started, arguing that Austria-Hungary itself had started the war and, consequently, Romania was under no formal obligation to join it. At the same time, Germany started encouraging Austria-Hungary to make territorial concessions to Romania and Italy in order to keep both states neutral.
In return for entering the war on Allied side, Romania demanded support for its territorial claims to parts of Hungarian Transylvania, and especially those parts with a Romanian-speaking majority. The Romanians' greatest concerns in negotiations were the avoidance of a conflict that would have to be fought on two fronts and written guarantees of Romanian territorial gains after the war. They demanded an agreement not to make a separate peace with the Central Powers, equal status at the future peace conference, Russian military assistance against Bulgaria, an Allied offensive in the direction of Bulgaria, and the regular shipment of Allied war supplies. The military convention they signed with the Allies stipulated that France and Britain should start an offensive against Bulgaria and the Ottoman Empire no later than August 1916, that Russia would send troops into Dobruja, and that the Romanian army would not be subordinated to Russian command. The Allies were to send 300 tons of provisions on a daily basis. According to the Romanian account, most of these clauses, with the exception of those imposed on Romania, failed to be respected.
The Allies accepted the terms late in the summer of 1916 ; Cyril Falls attributes the late decision to Romania's historical hostility towards the Russian Empire and purports that an earlier entry into the war, perhaps before the Brusilov offensive the same year, would have provided better chance for victory. According to some American military historians, Russia delayed approval of Romanian demands out of worries about Romanian territorial designs on Bessarabia, claimed by nationalist circles as a Romanian land. According to British military historian John Keegan, before Romania entered the war, the Allies had secretly agreed not to honour the territorial expansion of Romania when the war ended.
In 1915, Lieutenant-Colonel Christopher Thomson, a fluent speaker of French, was sent to Bucharest as British military attaché on the initiative of Lord Kitchener to bring Romania into the war. Once there, he quickly formed the view that an unprepared and ill-armed Romania facing a war on two fronts would be a liability, not an asset, to the Allies. This view was brushed aside by Whitehall, and Thomson signed a Military Convention with Romania on 13 August 1916. Within a few months, he had to alleviate the consequences of Romania's setbacks and supervise the destruction of the Romanian oil wells to deny them to Germany.
The Romanian government signed a treaty with the Allies on 17 August 1916 that pledged to declare war on Austria-Hungary by 28 August. The Romanian ambassador in Vienna actually transmitted the declaration of war on 27 August. Germany, caught by surprise, responded with a declaration of war on Romania the next day. The dates of the Bulgarian and Ottoman declarations of war are disputed. Ian Beckett says that Bulgaria did not issue a declaration of war prior to its attack of 31 August. Other sources place the declaration on 30 August or 1 September. The Ottoman declaration took place either on 29 August, 30 August or 1 September. Within two days of her own declaration, according to one source, Romania found herself at war with all the Central Powers.
File:WWI Poster Rumania.jpg|thumb|150px|British poster, welcoming Romania's decision to join the Entente
The Romanian Army was quite large, with over 650,000 men in 23 divisions, but it suffered from poor training and equipment, particularly when compared to its German counterparts. Meanwhile, the German Chief of Staff, General Erich von Falkenhayn, had correctly reasoned that Romania would side with the Allies, and had made plans accordingly. Thanks to the earlier conquest of the Kingdom of Serbia and the ineffective Allied operations on the Greek border, and having a territorial interest in Dobruja, the Bulgarian Army and the Ottoman Army were willing to help fight the Romanians.
The German high command was seriously worried about the prospect of Romania entering the war, Paul von Hindenburg writing:
It is certain that so relatively small a state as Rumania had never before been given a role so important, and, indeed, so decisive for the history of the world at so favorable a moment. Never before had two great Powers like Germany and Austria found themselves so much at the mercy of the military resources of a country which had scarcely one twentieth of the population of the two great states. Judging by the military situation, it was to be expected that Rumania had only to advance where she wished to decide the world war in favor of those Powers which had been hurling themselves at us in vain for years. Thus everything seemed to depend on whether Rumania was ready to make any sort of use of her momentary advantage.
Romanian armaments industry
Between 1914 and 1916, 59 Romanian factories produced 400,000 artillery rounds, 70 million bullets, 1,500 caissons, and 332 gun carriages. Grenades were also manufactured, with three factories producing 1.5 tons of explosives daily. The 332 gun carriages were produced in order to convert Romania's 53 mm and 57 mm Fahrpanzer fortress guns into field artillery. Some of the 57 mm guns were converted into anti-aircraft guns using a carriage designed by the Romanian General Ștefan Burileanu.The Romanian army badly lacked arms and ammunitions during the war, due to the industrial underdevelopment of the country.