The Abadan Crisis was a major event in the history and development of modern Iran. The crisis began in 1951 after the Iranian government, under the democratically elected Prime Minister, Mohammad Mosaddegh, nationalized the British owned Anglo-Persian Oil Company, including the Abadan Refinery. In 1901, local Iranian sovereigns had sold an oil concession covering much of the country's southwest, to William Knox D'Arcy, by the time oil was discovered in commercial quantities in May 1908, D'Arcy was nearly bankrupt and sold his rights to the Anglo-Persian Oil Company in 1909. In the decades that followed the British profited immensely from the concession returns, local Iranians employees labored in often abysmal conditions while the APOC earned millions of pounds. The British hid the earnings of APOC from the Iranian government and refused to comply with the profit-sharing terms they had been agreed to.
The nationalization of the Anglo-Iranian Oil Company's assets namely oil refinery in Abadan infuriated the British Government who imposed a blockade of Iranian oil exports and began conspiring to overthrow the elected government. Eventually, the CIA orchestrated a successful coup in 1953, which enabled the Shah to rule autocratically for the next 26 years.