The chain of events that brought the Korean peninsula to the outbreak of war in 1950 can be traced back to almost half a century before, at the beginning of the Japanese occupation of the country. The Korean nation, with a shared culture, language, ethnicity and heritage, deteriorated from harmonious social cohesion to a bloody civil war in just 40 years. The scars of the conflict are still etched on the Korean political landscape today. The North has a reclusive communist government, while the South has flourished as a democratic republic.

To understand the rapid deterioration and ultimate segregation of the peninsula, we must examine the conditions of the Japanese occupation of the country. Koreans under Japanese rule were a systematically divided and oppressed population. They saw their culture suppressed and their workforce mobilized to feed Japanese mouths and drive the Japanese war machine. But the period also gave birth to the Korean independence movement and began to shape Korean nationalism. Nationalist ideas would begin to be formed, both within Korea itself, across the Yalu River in China, and within the Soviet Union by those in exile. These same ideas which were bred under Japanese rule are those that gave the peninsula the political divide we can still see today.

The Japan-Korea Annexation Treaty of 1910

After formally becoming a Japanese protectorate in 1905 and handing over control of administrative affairs to the Japanese in 1907, Japanese Resident General Count Terauchi Masatake drew up the Japan-Korea Annexation Treaty in 1910, to formally transfer the governance of Korea to the Emperor of Japan. When presented with the treaty, Emperor Sunjong of Korea had no intention of signing it. But, with the ominous threat of Japanese invasion looming if he didn’t, he reluctantly placed his national seal of the Korean Empire on the treaty and, rather than sign it himself, presented Prime Minister Lee Wan-yong with the document to sign[i].

Sunjong faced the dilemma of either signing the document and accepting Japanese rule, or resist and be taken by force, which would undoubtedly have left many casualties and led to a more submissive relationship under the Japanese government. The fact the Emperor himself didn’t actually sign the document, and the conditions of duress that the document was presented under, has led many subsequent governments of both South and North Korea to question the legality of the treaty.

Life under Japanese rule

Despite the Emperor’s seal, the Koreans were treated as conquered people. The Japanese implemented their version of military rule, known asbudan seiji[ii]. The military and police extended their control into every aspect of Korean life. Koreans were not allowed to publish their own newspapers or organize their own political groups[iii], nor were they included in high levels of government administration. Korean land was frequently confiscated by the Japanese and redistributed.

Economically, the Japanese implemented a system of protectionist capitalism. They used Korean labor to drive Japanese industries. Koreans found themselves working in Japanese-owned firms. Any profits were sent back to Japan[iv] and only a very small and select group of Korean elites became successful under Japanese rule. In 1942, Korean entrepreneurs owned just 1.5% of the total capital invested in Korean industries and they were charged interest rates up to 25% higher than their Japanese counterparts[v]. These conditions made it impossible for the Korean working class to improve their lot and eroded the wealth of the already established middle class.

The Japanese occupiers wanted to ensure total stability and control on the peninsula, which would provide a buffer area between them and Chinese aggression[vi]. Their intention was to use the Korean peninsula to expand into north