The history of Latvia, like that of its neighbour Estonia, is largely one of foreign occupation. The indigenous Balts were overwhelmed at the start of the thirteenth century by German crusading knights, who massacred and enslaved them in the name of converting them to Christianity. The Germans continued to dominate both land and trade even after political control passed to the Polish-Lithuanian Commonwealth, then Sweden and finally Russia. During the second half of the nineteenth century the Latvians began to reassert their identity, achieving independence in 1918-20 after a war in which – with Estonian help – they beat off both the Soviets and the Germans. This hard-won independence was extinguished by Soviet annexation in 1940. As conditions in the Soviet Union relaxed during the late 1980s demands for increased autonomy turned into calls for outright independence, and on August 21, 1991, as the attempted coup against Gorbachev disintegrated in Moscow, Latvia declared its independence for the second time.