The Russian military tried to impose authority by building a series of forts, but these forts in turn became the new targets of raids and indeed sometimes the highlanders actually captured and held the forts. Under Yermolov, the Russian military began using a strategy of disproportionate retribution for raids. Russian troops retaliated by destroying villages where resistance fighters were thought to hide, as well as employing assassinations, kidnappings and the execution of whole families. Because the resistance was relying on sympathetic villages for food, the Russian military also systematically destroyed crops and livestock and killed Circassian civilians. Circassians responded by creating a tribal federation encompassing all tribes of the area. In 1840 Karl Friedrich Neumann estimated the Circassian casualties at around one and a half million. Some sources state that hundreds of thousands of others died during the exodus. Several historians use the phrase "Circassian massacres" for the consequences of Russian actions in the region."In a series of sweeping military campaigns lasting from 1860 to 1864... the northwest Caucasus and the Black Sea coast were virtually emptied of Muslim villagers. Columns of the displaced were marched either to the Kuban plains or toward the coast for transport to the Ottoman Empire... One after another, entire Circassian tribal groups were dispersed, resettled, or killed en masse" Circassians established an assembly called "Great Freedom Assembly" in the capital city of Shashe (Sochi) on June 25, 1861. Haji Qerandiqo Berzedj was appointed as the head of the assembly. This assembly asked for help from Europe, arguing that they would be forced into exile soon. However, before the result was achieved, Russian General Kolyobakin invaded Sochi and destroyed the parliament and no country opposed this.