Persia (now Iran) is a country in south-west Asia. In the 19th century both Russia and Britain were keen to increase their influence over the Qajar dynasty in Persia. A revolution in December 1905 resulted in the introduction of modern reforms. Two years later Russia and Britain negotiated a new agreement with the Persian government. The Anglo-Russian Entente divided the country into sphere of interest, giving Britain economic control of the south and Russia the north. There was also a neutral zone in the centre that included Tehran. In 1909 the Anglo-Persian Oil Company (later BP) was founded and this helped to reinforce Britain's control over the southern part of Persia.
During the First World War Germany attempted to remove Britain and Russia from Persia. In the First World War. In 1915 Russia sent an army led by General Baratov to protect their economic interests in Persia. Baratov gradually forced the German soldiers from the north of the country.
Britain's main concern was to guard the Anglo-Persian oil refineries in the south of Persia. The British formed the South Persia Rifles and by the end of 1916 they had eliminated German influence over that part of the country.
After the Russian Revolution in 1917, pro-German tribesmen under Kuchik Khan rebelled against the Russian forces in the north of the country. Britain sent General Dunsterville and an elite group of British, Canadian, Australian and New Zealand soldiers from Mesopotamia. The Dunsterforce, as they became known, were soon able to regain control of the country.
The behaviour of the South Persia Rifles upset the Persian government and they were expelled in the spring of 1918. The following year an agreement was signed which secured British supervision of oil supplies from Persia.