During the 19th and early 20th centuries, Korea was caught in the middle of Western and Eastern military and diplomatic power plays. China, which saw itself as Korea's protector in the region, perceived Japan's expansionism and Russia's commercial advances as threats to its economic and cultural dominance over Korea.

These regional tensions erupted into two wars, the Sino-Japanese War of 1894-95 and the Russo-Japanese War of 1904-05. Japan emerged victorious from both wars, establishing its predominance over the peninsula.

In 1910, Japan annexed Korea into its growing empire and began intensive reforms to "modernize" the isolationist country. As part of this "assimilation policy," Tokyo seized property from the Korean elite, instated Japanese as the official language and required Koreans to pay homage to Japanese emperors. Japan also established the Government-General to administer Japanese policies and rule Korea.

Japan's harsh policies brought about the rise of organized resistance movements and Korean nationalism. One resistance group, known as the March 1st Independence Movement (also called the Samil Movement), issued a proclamation of independence from Japanese rule and organized numerous nationwide uprisings, beginning on March 1, 1919. On that day alone, "thousands of lives were lost" in clashes with Japanese security, the South Korean Embassy in Washington D.C. notes on its Web site.

The uprisings lasted for an entire year before Japanese forces suppressed the opposition movement, jailing and killing "about 7,500 Koreans and wounded nearly 16,000," according to SouthKorea's official information service.

During the 1920s and 1930s, the Government-General also cracked down on Korea's burgeoning socialist and union groups, whose members sought to end Japan's harsh rule and labor regulations.

According to the North Korean worker party's official history, these groups evolved into a political armed group determined to liberate the nation from the Japanese, setting the foundation for Korea's future communist ideology. The future North Korean leader Kim Il Sung led an armed resistance group that organized unions against the Japanese elite, according to the official history.

At times, the socialist and nationalists groups united to try to overthrow the Japanese, such as the June 10, 1926 massive nationwide student protest.

In 1940, Japan, then occupying parts of Asia including French Indochina -- modern-day Vietnam -- joined with the Axis forces (Germany and Italy) in a world war against Allied powers, which included France and Britain and, later, the Soviets.

By 1944, as the war turned against the Japanese, the Government-General placed tough new production quotas on Korean factory and farm laborers for additional food and military supplies.

The Japanese also drafted Korean men and boys for military service, dispatching over 5,000 Koreans to fight on the borders with China and the Soviet Union. Meanwhile, a relatively small number of Korean guerrilla fighters joined Soviet and Chinese communist armies to battle the Japanese forces, the South Korean Information Service says.

Though Korea was not directly involved in World War II, the end of the war would have a dramatic impact on the region.

-- Compiled by Liz Harper for the Online NewsHour