In May 1901, William Knox D'Arcy was granted a concession by the Shah of Iran to search for oil which he found in May 1908. This was the first commercially significant find in the Middle East. On 14 April 1909, the Anglo-Persian Oil Company was incorporated to exploit this find. The company grew slowly until World War I when its strategic importance led the British Government to acquire controlling interest in the company and it became the Royal Navy's chief source of fuel oil during World War I.
In 1917, the war allowed it to take the British arm of the German Europäische Union, which used the trade name British Petroleum. After the war ended, the company, in which the British Government now had a 51% interest, moved to secure outlets in Europe and elsewhere. However, its main concern was still Persia, following the Anglo-Persian Agreement of 1919 the company continued to trade profitably in that country.