Romania was a autonomous principality within the Ottoman Empire until it gained independence in 1877. A constitutional monarchy, King Carol I (a relative of Kaiser Wilhelm II) ruled the country in 1914. After the Second Balkan War in 1913 Romania's size increased to 140,000 square kilometres.

Romania's economy was primarily based on agriculture and its 7.5 million population were mainly concentrated in the fertile Wallachian Plains. Romania depended heavily on trade with Germany. Its other powerful neighbour, Austria-Hungary, was unpopular as it was believed that the government had done very little to stop the maltreatment of 3 million Romanians in Transylvania. All adult males spent time in the territorial reserve but the Romanian Army contained less than 100,000 men.