Karl Marx was a German philosopher, economist, sociologist, historian, journalist, and revolutionary socialist. He developed the ideas of Communism and wrote The Communist Manifesto and Das Kapital with Friedrich Engels.
Vladimir Lenin was the premier of the Soviet Union, and the leader of the Bolshevik faction (majority faction) of Social Democrats. He took a senior role in orchestrating the October Revolution. He was politically a Marxist and his political theory is known as Leninism, which when paired with Marxist economic theory is known as Marxism-Leninism. He was born to a fairly wealth family before becoming a revolutionary and in his personal life was said to be a modest and unassuming man, who liked cats, amateur photography and cycling.
Josef Stalin (real name Iosif Vissarionovich Dzhugashivili) was born in Georgia, and in the Soviet Union was initially the People's Commissar for Nationalities Affairs. He played a big role in the 1921 Red Army Invasion of Georgia which led to the Georgian Affair of 1922. After Lenin's death in 1924 he rose to power and soon became the de facto Statesman.
Leon Trotsky was born in Yanovka, a small provincial town in 1879 to fairly wealthy Jewish farmers. His birth name was Lev Davidovich Bronshtein and he adopted the name Leon Trotsky whilst escaping from exile. He was too a Marxist. Initially he was a Menshevik (the minority faction in the Social Democrats) but became a Bolshevik prior to the October revolution of 1917. And in the Soviet Union was the Peoples Commissar for Foreign Affairs, before becoming the first ever Leader and Commander of the Red Army. He played a large part in the October revolution alongside Vladimir Lenin. He was exiled by Stalin in 1929, and assassinated by a Stalinist assassin in Mexico, 1940. In his personal life however, he could be overbearing, aloof, and came across as arrogant.
The KGB were the security agency of the Soviet Union from 1954 until the end of 1991. The committee was a direct successor of such preceding agencies as Cheka, NKGB, MGB. It was the chief government agency of "union-republican jurisdiction" in the fields of internal security, intelligence, and secret police.
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