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.
Romania's peacetime army was manned by limited conscription, and all adult males spent time in the territorial reserve. This gave it a regular strength of around 100,000 men. On the outbreak of the Second Balkan War in 1913, conscription was introduced and the Romanian Army grew to 400,000.
In August 1916, Romania joined the Allies against the Central Powers. Within weeks Germany responded by invading Romania and by the end of the year controlled Wallachia and Dobrudja and most of the country's natural resources including its oil supplies.
After Russia withdrew from the fighting Romania was placed in an impossible situation and in December, 1917, the prime minister announced a ceasefire. Under the Treaty of Bucharest, Romania became a virtual economic colony of the Central Powers. Germany stripped the country of food and raw materials and it is estimated that the occupation led to the deaths of 500,000 civilians.
During the Paris Peace Conference Romania made territorial claims and as a result of the treaties of Neuilly and Trianon, gained Transylvania, Bessarabia and much of the Hungarian plain, and almost doubled in size.
After the war internal politics were corrupt and a strong fascist party, the Iron Guard, eventually gained power. There was frequent bouts of anti-Semitism and during the Second World War allied itself to Nazi Germany.
Romania participated in Operation Barbarossa and suffered heavy casualties at the hands of the Red Army. When Soviet forces reached the borders of Romania in 1944 Michael I decided to change his alliances and on 25th August he declared war on Germany.
In 1945 Soviet forces occupied Romania and in November a predominately communist government was installed. Two years later Romania became a People's Republic.