In the aftermath of the Russian Revolution, Persia had become a battleground. In 1917, Britain used Iran as the springboard for an attack into Russia in an unsuccessful attempt to reverse the Revolution. The Soviet Union responded by annexing portions of northern Persia, creating the Persian Socialist Soviet Republic. The Soviets extracted ever more humiliating concessions from the Qajar government, whose ministers Ahmad Shah was often unable to control. By 1920, the government had lost virtually all power outside its capital: British and Soviet forces exercised control over most of the Iranian mainland.