The Japanese occupation of Korea is a dark and tragic period of contemporary Korean history that stretches all the way to 1945.
Korea became a colony of Japan in 1910 after Russia lost the Russo-Japanese War in 1905. Infrastructures were created, but for the sole reason of Japan better exploiting their colony. The benefits of these did not by any means reach out to the Koreans, who were treated harshly.
The Revolutionary Martyrs' Cemetery in Pyongyang has bronze busts of DPRK National Heroes who dedicated their lives to fighting against the Japanese
Taxes were introduced in order to overthrow local tenants (those who refused to pay were killed), with the sole purpose of sending rice to Japan. This led to famines. People were used as slaves for public infrastructure work and thousands of women were sent abroad and forced to act as "comfort women" for Japanese soldiers. Moreover, Japanese military control increased whenever Koreans tried to rebel against the colonial presence.
Once the war broke with China in 1937 and the Second World War started, the Japanese tried to completely erase Korea as a nation. Japanese was taught in school, Korean history was not and it was forbidden for people to write or speak in their own language. People were also forced to have Japanese names. Many Korean historical relics were sent to Japan, where many still remain.
This caused strong resentment of the Korean people towards the invading power, Japan, feelings that can still be felt to one extent or another in both South and North Korea.
Korea was liberated on 15 August 1945. This date is celebrated both in North and South Korea.