In 1919, he established the Comintern (Communist International). The Comintern united all Marxist groups throughout the world who accepted Lenin’s ideas on revolutionary violence and Communist Party organization.

The only Communist government established with the help of the Comintern was in Outer Mongolia (now called Mongolia) in the early 1920’s. The Comintern succeeded there partly because Mongolians feared domination by the Chinese more than by the Soviets. Stalin had little faith in the Comintern, and he dissolved it in 1943.

The international instability that resulted from World War II provided opportunities for Communist gains in many countries. In 1939, the Soviet Union and Germany signed a nonaggression pact, an agreement in which they promised not to attack each other. A secret provision of the pact declared that certain areas in Europe would be divided between the two countries. In 1939 and 1940, the Soviet Union took over the Baltic countries of Latvia, Lithuania, and Estonia, and parts of Poland, Finland, and Romania. All of this territory became part of the Communist Soviet Union.

Toward the end of the war, the Soviet Union helped free many countries from German and Japanese control. The presence of Soviet troops enabled the U.S.S.R. to set up Communist-controlled governments in several of these countries, including Bulgaria, East Germany, Hungary, Poland, Romania, and North Korea. Winston Churchill, the former British prime minister, warned in 1946 that an “iron curtain” had descended across Europe, dividing eastern Europe from western Europe. Although supposedly independent, the Iron Curtain countries were actually Soviet satellites (countries controlled by the Soviet Union). The satellites had to follow Soviet foreign policy and adopt Communist political and economic practices.

In some other countries, Communists who had led national resistance movements during World War II grew stronger. Local Communists took over the governments of Albania, Yugoslavia, and Vietnam near the end of the war with little or no help from the Soviets. A Soviet-supported Communist regime gained complete control in Czechoslovakia in 1948. Communists also became important political forces in France and Italy.

In China, the Communists and the ruling Nationalist Party both fought the Japanese, who had invaded the country during the 1930’s. After World War II, a civil war broke out in China between the Communists and the Nationalists. The Communists, led by Mao Zedong, gradually gained control by winning widespread peasant support in the countryside. By 1949, they had taken over mainland China.

From the late 1940’s to the 1960’s, most other attempts by Communists to take power failed. For example, Communists in Greece, Malaya (now part of Malaysia), and the Philippines fought guerrilla wars but failed to gain power. Armed forces from Communist North Korea invaded non-Communist South Korea in 1950. The invasion resulted in a three-year war between the North Koreans backed by Communist countries and the South Koreans backed by non-Communist nations. Neither side won complete victory in the Korean War (1950-1953), and Korea remained divided between a Communist north and a non-Communist south.

The only major gain by Communists during this period occurred in Cuba. Fidel Castro became dictator of Cuba in 1959, and two years later, he declared his government to be Communist.

In 1946, the Communist leader Ho Chi Minh led a nationalist uprising in the colony of French Indochina. By 1954, Indochina had been divided into Communist North Vietnam, non-Communist South Vietnam, and neutral Cambodia and Laos. Communists in Cambodia, Laos, and South Vietnam continued to fight the new non-Communist or neutral governments. North Vietnam sent troops and supplies to help the Communists, and China and the Soviet Union also sent equipment.

The struggle in South Vietnam developed into a major conflict, the Vietnam War (1957-1975). The United States sent troops to support South Vietnam. A cease-fire agreement ended U.S. participation in 1973, but the war continued until the Communists won full control of South Vietnam in 1975. In 1976, the Communists unified North and South Vietnam into the single nation of Vietnam. Communists also conquered Cambodia in 1975. In Laos, the government came under Communist control in 1975.

In Africa, a left wing military group controlled the government of Ethiopia from 1974 to 1991. The military government adopted socialist policies and developed close relations with the Soviet Union. In 1975, leftist guerrilla forces formed Marxist-Leninist governments in Angola and Mozambique. They controlled the governments of these countries until 1990. Other African nations had Marxist-Leninist governments for short periods in the 1970’s and 1980’s. In Central America, an alliance of Marxist-Leninist groups called the Sandinista National Liberation Front held power in Nicaragua from 1979 to 1990. In 1990, however, a candidate backed by 14 anti-Sandinista parties won Nicaragua’s presidential election.

In southwestern Asia in 1978, a Marxist-Leninist party seized power in Afghanistan. However, many Afghans rebelled against the new government. In 1979, the Soviet Union sent troops into Afghanistan to prevent the overthrow of the government. The invasion resulted in a lengthy conflict between Soviet troops and Afghan rebels. The Soviet occupation of Afghanistan ended in 1989. The rebels overthrew the government in 1992.