Who is Andrei Andreyevicy Vlasov from The Gulag Archipelago, 1918-1956 and what is their importance?

A lieutenant general in the Red Army, Vlasov in 1942 surrenders to the Germans after his 2nd Shock Army penetrates the lines in trying to relieve Leningrad, but is not reinforced, forbidden to surrender, and is decimated. Vlasov switches sides to lead renegade Russian forces against the Soviets. He is handed over to the USSR by the Allies and executed in 1946. The name Vlasov becomes synonymous with traitor. When Solzhenitsyn is arrested, passersby assume he is a captured Vlasov man and revile him. In the spring of 1945, only the Vlasovites fail to question why prison is their fate and anticipate a general amnesty.