After the Brusilov Offensive, Romania, which had been long courted by the Entente, but had until then chosen to stay neutral, entered the war. Romania’s primary goal was acquiring Transylvania from Austro-Hungary. Thus it was that the first military action of the Romanian army was the invasion of Transylvania through the Carpathian passes. The Central Powers response came swiftly, pushing the Romanians out of Transylvania and invading the country from the west and south. The capital, Bucharest, was conquered. All told, the Romanian interlude was a disaster for the Entente and a morale-boosting victory with very tangible rewards for the Central Powers.
The Entente had long been wooing Romania, which had an interest in joining the war. This interest was Transylvania, Hungarian-ruled, but mostly Romanian-populated. However, Romania could only hope to get it if the Entente won, and up to mid-1916 that did not look very likely. Besides, should a Central Powers victory put Transylvania out of reach, Russian Bessarabia (now the Republic of Moldova), also mostly Romanian-populated, could be a consolation prize. Strategic vulnerability also dictated caution. Romania had very long frontiers relative to its area, and its neighbours from the West and South were already in the Central Powers camp.
A military convention was signed, providing for extensive Entente assistance, both financial and military. The Romanian divisions would, it was thought, decisively affect the eastern front as a whole. In exchange, after the war Romania would receive territories from the defeated Austro-Hungary.
The Entente’s analysis of German losses led them to the conclusion that Germany was on the verge of collapse. And thus the importance of Romania. Verdun was Germany’s last-ditch offensive. If it failed, Germany would collapse. How could it be made to collapse faster? Clearly only so much could be expected from Russia at this point. But Romania had a sizeable army, well in excess of half a million men, which could bring the Germans to their breaking point. The problem was that the Entente’s estimates of German capabilities were wrong, and the German army in 1916 was nowhere near its breaking point.
The Romanian army numbered 23 divisions, but all were poorly equipped and deficient in wheeled transport; the road system was inadequate, and the railways not much better. Most Romanian soldiers were illiterate and ill-trained. The officers lacked experience, and were also inclined to panic. As things turned out, it was the Russians, and not the Central Powers, who suffered from a Romanian ulcer. Almost a third of the Russian army had to be diverted to the south. This did not save Romania.
Russian troops were pinned to the Kowel and Galician offensives; half of them were placed north of the Pripyat with almost nothing to do. Mikhail Alexeyev himself, the Russian Chief of Staff, had been told again and again that Romanian intervention would be decisive. Russian diplomats had been induced to promise Romania the areas of Austria-Hungary she coveted, and later on the Entente connived at Romania’s acquisition of Russian territory, Bessarabia. Alexeyev himself generally felt that Romanian intervention was not worth this much – on the contrary, it would be a liability.
One division was left to guard Dobrudja, and almost all the rest were sent into Transylvania. Hungary had few troops there, a few days would suffice to take it, and then Dobrudja could be reinforced. However, as insurance, the Romanian High Command asked Russia for troops and Alexeyev agreed to send to Dobrudja the minimum three divisions specified by the Russo-Romanian military convention. Unfortunately, this proved only the first, and smallest, burden that Romania's entry into the war imposed on Russia.
The Romanians opened an offensive, not, as the commanders in Salonika had expected, against Bulgaria, where it might have lent support to and been supported by their own, but into Hungary through the passes of the Transylvanian Alps. The Romanians occupied Southern Transylvania, but the Central Powers retaliated quickly.
Newly installed as the German Chief of Staff, Paul von Hindenburg reacted immediately. He used the unified command established in the Eastern Front to good effect. Two armies were swiftly established from disparate elements of German, Austrian, Bulgarian and Turkish units: one, the Army of the Danube, was to be commanded by August von Mackensen and would invade Romania from their Bulgarian frontier in the south; the other, the German Ninth Army, would first rebuff the Romanian invasion of Transylvania, then invade Romania from the west. This would be led by Erich von Falkenhayn.
The Romanians did not expect the attack in the South. First, they thought that the Western Powers forces in Salonika would pin down most of the Bulgarian army. This was not the case. The attack from Salonika was a complete failure, and did not prevent Germans, Turks and Bulgarians from concentrating a substantial force against southern Romania. The Romanians had also expected Bulgaria to be deterred by the presence of a Russian force, Zayonchkovski’s, in the Dobrudja. In theory, the Bulgarians were Russophile; some even thought they might make peace once Romania entered the war on Russia’s side. This again was not the case.
Bulgaria declared war on Romania, and a mixed force under Mackensen immediately invaded Dobrudja. The Romanian fortress at Turtucaia fell after only a day of fighting. With it the way was open for the Central Powers to move forward, sweeping the Romanian division aside, reducing the 1st Serbian and 61st Russian divisions to 3,000 men each, and forcing them out.
Silistra also had fallen, this time without even spoken resistance. The Bulgarians and their allies crossed the border and invaded Dobrudja. Here they were due to encounter Russian forces. But the collaboration of Russians and Romanians almost constituted an object-lesson in how not to run a multinational force. General Andrei Zaionchkovsky, though doing his best to maintain polite forms, complained again and again to Alexeyev that his task was impossible: to make the Romanian army fight a modern war was asking a donkey to perform a minuet. It did not help matters when Russian troops started looting from the local population.
Faced with an invasion from the south, and the potential loss of their only sea port, the Romanians had to make some hard choices: put everything into an attack into Transylvania, or try to eject von Mackensen from Dobrudja. Although the actual decision is usually thought of as wrong, it’s difficult to see what real options the Romanians had at this point. So they tried to mount operations in both directions, a plan for which they lacked the necessary resources.
Threats to Dobrudja compelled the Romanian High Command to think again. A Crown Council in Bucharest determined that operations in Transylvania should be suspended, to permit the transfer of half of the army against Bulgaria. A ‘Southern Army Group’ would be assembled under General Alexandru Averescu to cross the Danube into Bulgaria. Meanwhile, Zayonchkovski’s Russo-Romanian force would contribute an offensive against the Bulgarians who had arrived in Dobrudja.
In an effort to stop the Central Powers advance in southern Romania, an attack was to be made between Zimnicea and Flămânda. The goal was for the Romanians to cross the Danube and attack enemy positions there. It was a burlesque. The Flămânda enterprise had to be abandoned because this strategic maneuver had been achieved at the cost of Romanian positions in Transylvania. In Dobrudja, things took a similar course, with the complication that Romanians misunderstood Russian orders, and in any case were not keen on obeying them.
Von Falkenhayn, the new theater commander, arrived in Transylvania bringing with him the nucleus of a sizeable Austro-German force, subsequently known as the Ninth Army. He was as little hindered as Mackensen. By the end of October Falkenhayn had forced the Romanian troops to retreat from Transylvania by his win at Kronstadt, today known as Brașov. Despite assurances of the British High Command in London that the Carpathians were impassable if defended, by the middle of November the Germans had broken through the passes and were in the Romanian plains heading toward the capital, Bucharest.
Transylvania was once more virtually completely in the hands of the Central Powers. Now Falkenhayn could cross the mountains into Wallachia and join up with Mackensen’s forces on the Danube. To avoid this, the Romanians decided to take back from the Danube the troops they had sent in the second half of September. In the short term, this succeeded. The passes into Wallachia were blocked, and throughout October Falkenhayn’s groups had a difficult time, pushing through the snow from one defense-position to another on their way through the mountains.
On the southern front, the Central Powers offensive achieved considerable results. An offensive into Dobrudja was prepared and launched, mainly with Bulgarian and Arab divisions. Zayonchkovski’s army had not been strengthened. Defense of the Dobrudja province was another piece of burlesque. Bombardment struck the Romanians on the right, who retired without informing the Russians in the center. In no time, the railway line between Cernavoda and Constantza, the main Romanian port, was broken. Constantza itself was not defended.
Alexeyev now began to recognize that he would have to do something. Elsewhere on the front the Kowel offensives had failed, and attacks in eastern Galicia were also dying down in failure; now the Central Powers had almost reached the Danube delta, and seemed to threaten southern Russia. Stavka first sent VIII Army to the Dniester, and then agreed to send another army to constitute, ‘Army of the Danube’ with a view to the defense of the delta and Galați. Finally, IV Army was earmarked for Romania. In the end the Russian armies would arrive too late for Romania’s capital, Bucharest.
Early in November, German troops penetrated the passes into the western part of Wallachia — Oltenia — and by mid-November had reached the plains. A cavalry corps moved east towards Bucharest, dislodging the defenders from the southern parts of other passes. The German-Bulgarian force crossed the Danube, and found the task easy enough, since the Romanians had now diverted most of their forces back to the Carpathian front. By the end of November the two armies of the Central Powers were threatening Bucharest.
There was a final episode of drama. The Romanians had now been sent a French military mission, under Henri Berthelot, Joffre’s chief of staff during the battle of the Marne. He had visions of a Balkan Marne: a flank-attack on the Germans as they approached Bucharest, crossing the Argeș river. Berthelot built up a masse de manoeuvre: divisions scraped from the Danube and the Carpathians. The Romanian soldiers were driven forward into an affair that only consumed what was left of the reserve divisions. The Germans repelled ‘the Romanian Marne’ easily enough.
Mackensen's army had crossed the Danube and was approaching Bucharest. The Romanian capital promptly fell into German hands. Assailed on three sides by four enemies, for the Turks had sent two divisions by sea to Dobrudja, the Romanians had been thrown into full retreat toward their remote eastern province of Moldavia, between the Siret River and the Russian border. There, as winter closed in, and with support from the Russians, they entrenched themselves on the Siret to sit out the bad weather.
The Russian South-West Front's mission was no longer to eliminate Austro-Hungary, but to prevent Romania's complete collapse. The onset of winter brought little relief. Defense of the Romanian front became Stavka's main preoccupation because failure could open the way into Ukraine and the Russian rear. All offensive plans were scrapped.
On the Russo-Romanian side, there was also little appetite for action. The Romanian army had been put to flight; it could count on a manpower reserve of less than 250,000 men, most of them quite untrained. The Russians, who now dominated the area completely, had no stomach for further offensive action. Their only action of any scale between early January and the Kerensky offensive of midsummer was a stroke on the Baltic coast.
The Central Powers conquered the country easily enough, and, in the next year and a half, removed far more from it than they could have done had it remained neutral: over a million tons of oil, over two million tons of grain, 200,000 tons of timber, 100,000 head of cattle, 200,000 goats and pigs, over and above the quantities requisitioned for maintenance of the armies of occupation. Romanian intervention, in other words, made possible the Germans’ continuation of the war into 1918. The essential reason for this, aside from the obvious boost of resources, was the Central Powers’ capacity to shift their reserves quickly.
Alexeyev, in a rare flash of realism, actively discounted the value of the Romanians as allies, rightly reckoning that they would drain rather than add to Russian reserves. He certainly did little to assist them. Nor did the French and British at Salonika, whose undertaking to mount a diversionary offensive had been a major consideration in bringing Romania to declare war. However, that does not excuse the Romanians’ entry into a war for which they were ill-equipped and ill-prepared. Their decision for war had been disastrous. They had lost 310,000 men - nearly half as prisoners - and almost the whole of their country.