Romania's Attack On Austria-Hungary: Why And When?

On August 27, 1916, Romania declared war on Austria-Hungary, formally entering World War I. Romanian troops crossed the border of the Austro-Hungarian Empire into the much-contested province of Transylvania, which was ethnically Romanian but then part of Hungary. Romania's primary motivation for entering the war was to realign boundaries of the national state, as Austria-Hungary had captured provinces with significant Romanian populations. Romania's invasion of Austria-Hungary in 1916 was not its first, nor its last. In 1918, Romania re-entered the war with similar objectives to those of 1916, and in 1919, during the Hungarian–Romanian War, Romania occupied Hungary.

Romania's motivation to enter the war

Romania's decision to enter World War I in August 1916 on the side of the Allies was motivated primarily by the desire to claim the region of Transylvania and its majority ethnic Romanian population from the Austro-Hungarian Empire. The Kingdom of Romania had long been at odds with Austria-Hungary over the issue of territory, specifically Transylvania, which was ethnically Romanian but part of Hungary.

Romania's entry into the war was also influenced by its desire to unite all the territories in which a Romanian population existed in a single state. This included the province of Bukovina, which was under Austro-Hungarian control. Additionally, Romania sought to capitalize on Russia's success against Austria on the battlefields of the Eastern Front during the summer of 1916 and make an advantageous entry into the war to realize long-held dreams of territorial expansion and national unity.

On August 18, 1916, Romania signed a secret treaty with the Allies, stipulating that in the event of an Allied victory, Romania would acquire Transylvania up to the River Theiss, the province of Bukovina up to the River Pruth, and the entire Banat region, all territories under Austro-Hungarian control. Romania's King Ferdinand I also proclaimed that the war presented an opportunity to give back his birthright of a "great and free Rumania from the Tisza to the Black Sea."

Furthermore, the Allies wanted Romania to join their side to cut rail communications between Germany and Turkey and to cut off Germany's oil supplies. Britain, France, and Russia offered loans, military training, and munitions to Romania, promising to defend Romania against Bulgaria and help it invade Austria-Hungary.

Romania's decision to enter the war was also influenced by the successes of the Russian Brusilov offensive against Austria-Hungary. The military campaign, led by General Alexei Brusilov, was a series of attacks against the Austro-Hungarian forces between June and September 1916, which resulted in significant losses for the Central Powers and boosted the morale of the Allies.

However, despite initial successes, Romania's campaign in Transylvania turned into a military disaster. The Central Powers, including Bulgaria, launched a counterattack, and by December 1916, two-thirds of Romania's territory, including its capital Bucharest, were occupied by the Central Powers.

The Battle of Transylvania

Romania had been bound by the pre-war Triple Alliance to the Central Powers but instead joined the Triple Entente in August 1916, following the signing of the Treaty of Bucharest. Romania's offensive was initially successful, but it was brought to a halt after Bulgaria's attack on Dobruja. A successful German and Austro-Hungarian counterattack, which started in mid-September, eventually forced the Romanian Army to retreat back to the Carpathians by mid-October. Despite this, the Romanian armies managed to escape the Central Powers' attempts to completely destroy them.

The Romanian 1st Army, commanded by General Ioan Culcer, crossed the border at the Surduc and Vulcan Passes and occupied Petrozsény (Petroșani) — the vital Transylvanian coal-mining centre — on 29 August, easily defeating the Hungarian coal-miner battalions and inflicting heavy casualties. The Romanian 2nd Army, commanded by General Alexandru Averescu, converged on Brassó (Brașov) through five mountain passes. The Romanian North Army had the largest number of soldiers of the three Romanian armies invading Transylvania. It was commanded by General Constantin Prezan.

The Romanian attack on Austria-Hungary

Romania's attack on Austria-Hungary during World War I began on 27 August 1916, when Romania declared war on Austria-Hungary and its troops crossed the border into the province of Transylvania. This marked Romania's formal entry into World War I as part of the Allied forces. The attack was driven by Romania's desire to gain territories belonging to Austria-Hungary with significant Romanian populations, particularly Transylvania.

In the lead-up to the war, Romania had been an ally of Germany and Austria-Hungary since 1883 as part of the Triple Alliance. However, in 1914, Romania declared its neutrality, much to the disappointment of its allies. During this time, internal debates raged within Romania, with "Germanophiles" advocating for alignment with the Triple Alliance, and "Entente supporters" pushing for joining the war against Austria-Hungary to liberate Romanian-populated territories. Eventually, the Entente supporters gained the upper hand, and Romania signed a secret treaty with the Allies on 18 August 1916.

The counter-attack by the Central Powers aimed to expel the Romanian forces from Transylvania and eliminate Romania as a military factor for the rest of the war. The First Army of confederate troops, led by Erich von Falkenhayn, pushed the Romanians back across the southern Carpathians into Valachia, while the 9th Army, under Field Marshal August von Mackensen, crossed the Danube from Bulgaria. By December 1916, the Central Powers had invaded Bucharest, the capital of Romania, and occupied much of the country. However, the Romanian court and government fled to Moldavia, where they reorganised with French military aid, keeping Romania in the war.

The counter-attack of the Central Powers

Planning and Initial Attacks:

• The Central Powers, recognizing the threat posed by Romania's entry into World War I on the side of the Allies, quickly mobilized their forces for a counter-attack. The overall command of the counter-offensive was under German General Erich von Falkenhayn, who had previously served as the German Chief of Staff.
• The counter-attack began in mid-September 1916, with German troops attacking the Romanian First Army near the town of Hațeg. This initial attack halted the Romanian advance and set the tone for the subsequent engagements.
• A few days later, German troops launched an assault on Sibiu, and by September 29, the outnumbered Romanians began a retreat to the Vulcan and Turnu Roșu passes. The Romanian forces put up a fierce resistance, and the Battle of Turnu Roșu Pass resulted in significant casualties on both sides.

Romanian Retreat and Central Powers Advances:

• The Romanian Second Army launched an attack on the Austro-Hungarians at Brașov on October 17, but this assault was repulsed, and the Romanians were forced to retreat. The Romanian Fourth Army, in the north, also retreated without much pressure from the Austro-Hungarian troops.
• By October 25, 1916, the Romanian army had retreated back to its initial positions, and the Central Powers had regained the strategic initiative in Transylvania. The Central Powers' ability to rapidly concentrate significant military forces and exploit Romanian weaknesses was a key factor in their success.
• The Central Powers' success in Transylvania was due to their ability to bring in reinforcements from other fronts and take advantage of the shift of Romanian units to the Dobruja battlefront. This allowed them to outmaneuver and outnumber the Romanian forces.

Battles in Southern and Eastern Carpathians:

• In October 1916, the Romanian army launched a large-scale operation to defend the mountain passes in the Southern and Eastern Carpathians against the advancing German and Austro-Hungarian forces. Some of the most intense fighting took place in the Prahova Valley, with the town of Predeal being a major objective for the Central Powers.
• The battles in this region were often compared to the heaviest fights on the Western Front, highlighting their significance and intensity. Similar fierce battles occurred in the Bran-Câmpulung area, especially at Dragoslavele and Racoș.
• The Romanian First Army, under General Ion Dragalina, put up a strong resistance in the Carpathians, supported by the local civilian population. One notable figure was Ecaterina Teodoroiu, who became known as the "Heroine of the Jiu" for her bravery during the Battle of Târgu Jiu.

German Advance and Romanian Retreat:

• Despite the Romanian army's initial successes in halting the German advance, the Central Powers regrouped and launched a new offensive in November 1916. The German High Command created the Army Group Kühne, led by General Viktor Kühne, which included infantry and cavalry divisions.
• The Romanian forces were unable to withstand this new assault, and on November 1, 1916, they began a retreat. The Romanian army continued to fall back, and on November 21, the German cavalry entered Craiova. The Romanian forces attempted to slow the German advance with battles such as the Battle of Robănești but were largely unsuccessful.
• The Central Powers, led by Field Marshal August von Mackensen, launched a new offensive in Dobruja in October 1916, achieving a decisive victory in the Second Battle of Cobadin. This resulted in the fall of Constanța and the withdrawal of Romanian and Russian forces from the region.

Fall of Bucharest and Romanian Retreat to Moldavia:

• The Central Powers, led by von Mackensen, advanced rapidly towards Bucharest, capital of Romania. The Romanian Command prepared a counter-offensive, known as the Battle of Argeș, to stop the advance and encircle von Mackensen's forces. However, due to a lack of Russian support, this offensive failed, and Bucharest was captured by von Falkenhayn's cavalry on December 6, 1916.
• The Romanian Second Army retreated to the Siret River, and by January 1917, two-thirds of Romania was occupied by the Central Powers. The Romanian forces regrouped and established defensive positions in Moldavia, with the impassable Danube Delta to their advantage.
• Despite heavy casualties and territorial losses, the Romanian army remained a formidable force, and their resistance prevented the Central Powers from achieving their goal of knocking Romania out of the war. The Romanian army's ability to reorganize and the support of the civilian population played a crucial role in their continued resistance.

The Treaty of Trianon

The Terms of the Treaty

By the terms of the treaty, Hungary lost at least two-thirds of its former territory and two-thirds of its population. The Kingdom of Romania received most of Banat and all of Transylvania, which had a significant Romanian population. Czechoslovakia was given Slovakia, Sub-Carpathian Ruthenia, and the region of Bratislava. Austria received western Hungary (most of Burgenland). The Kingdom of Serbs, Croats, and Slovenes (later Yugoslavia) took Croatia-Slavonia and part of Banat. Italy received the city of Fiume.

The treaty limited Hungary's army to 35,000 men, and the Austro-Hungarian Navy ceased to exist. Hungary also had to pay war reparations to its neighbours. The Allies rejected the idea of plebiscites to decide the fate of disputed territories, except in the case of the city of Sopron, which voted to remain in Hungary.

Reactions and Consequences

The treaty also had significant economic consequences, disrupting the economic interdependence that had existed within the Austro-Hungarian Empire. Post-treaty Hungary retained only about a third of the kingdom's pre-war territory and population but possessed 90% of its engineering and printing industry. The new borders bisected transport links, paralysing much of the rail cargo traffic. The loss of competitive industries, combined with customs barriers and fragmented protective economies, led to a deep recession in the region.

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