Korean Liberation and Founding, 1945–1948 — Division and the Birth of Two Republics

The period from Korea’s liberation from Japanese colonial rule on August 15, 1945, to the establishment of the Republic of Korea on August 15, 1948 — exactly three years — was one of the most consequential and traumatic in modern Korean history. It was a liminal, uncertain era in which Korea transitioned from colonial subjection to nominal independence but found itself divided between Soviet and American occupation zones, riven by ideological conflict, and ultimately fractured into two separate states. The decisions, accidents, and path dependencies of these three years shaped the geopolitical landscape of East Asia for the remainder of the 20th century and beyond. The generation born in the chaos of 1945–1948 — including Roh Moo-hyun, born September 1, 1946 — would grow up to contest, inherit, and ultimately reckon with the institutional legacies created in this foundational period.

The End of Japanese Rule and the Occupation Zones (August–September 1945)

Japan’s Sudden Surrender

Japan’s surrender on August 15, 1945 — announced by Emperor Hirohito in a radio broadcast — came after the atomic bombings of Hiroshima (August 6) and Nagasaki (August 9), and the Soviet Union’s entry into the war against Japan (August 8). Korea, which had been under Japanese colonial rule since 1910, was abruptly freed, but the transition was chaotic and unplanned.

Japan’s Korean colonial apparatus — the Governor-General’s administration, the colonial police, the military-industrial infrastructure — collapsed rapidly. Japanese settlers and military personnel began fleeing the peninsula. Korean political prisoners were released from colonial prisons. A power vacuum opened.

Soviet and American Occupation

The geopolitics of the liberated Korean peninsula were immediately contested. The Soviet Union, having declared war on Japan on August 8, 1945, rapidly deployed forces from Manchuria into northern Korea. Soviet forces moved down the peninsula swiftly, reaching Pyongyang and halting at the 38th parallel. The United States, which had been fighting Japan in the Pacific, had no troops immediately available for Korea. In a hastily arranged agreement in mid-August 1945, American and Soviet commanders agreed to divide Korea at the 38th parallel: Soviet forces would occupy everything north of this latitude; American forces would occupy the south.

This 38th parallel division (38도선 분할), originally intended as a temporary administrative convenience, would become the de facto frontier between two hostile states. Both occupations were initially understood by their architects as provisional — the peninsula would eventually be reunified under some form of agreed governance. This assumption would prove catastrophically wrong.

By early September 1945, Soviet forces occupied the Korean north; American forces arrived in south Korea later that month, landing at Incheon and establishing a military government under General John R. Hodge.

The American Military Government in South Korea (1945–1948)

The United States Army Military Government in Korea (USMGIK, 미군정) established in the American-occupied south was led by General John R. Hodge and characterized by:

Colonial Continuity

Rather than dismantling the Japanese colonial state apparatus, Hodge’s administration largely preserved Japanese colonial structures — the police (경찰), the bureaucratic hierarchy, the land tenure system — incorporating Japanese officials and Korean colonial collaborators into the American military government. This decision, intended to ensure administrative continuity and efficiency, proved politically explosive. Korean nationalists and leftists viewed the preservation of the colonial apparatus as a betrayal: Korea was liberated from Japan only to be ruled by America through the same instruments of oppression.

Korean police and bureaucrats who had collaborated with the Japanese empire during 1910–1945 were largely not purged or tried for collaboration, but retained in office. This became a festering grievance for many Koreans who saw the liberation as incomplete.

Suppression of Korean Autonomy

The military government dissolved Korean political organizations and suppressed Korean nationalism. Korean flags were initially banned; Korean newspapers were heavily censored. Political parties and civic organizations were monitored and controlled. The military government attempted to monopolize authority, viewing Korean political activity with suspicion.

Economic Policy and Land Reform

The American military government faced urgent economic questions: Korea’s economy, integrated into the Japanese empire’s raw-material and production system, was disrupted by the loss of Japanese investment and markets. The north, richer in mineral resources and heavy industry, was cut off from the south by the 38th parallel border.

Land reform was politically fraught. Tenant farmers (소작농), who worked land owned by Korean yangban elites and Japanese settlers, expected redistribution of land. However, the military government proved reluctant to undertake radical land reform, fearing communist organizing among poor peasants. The Japanese-owned lands were seized, but the disposition of Korean-owned lands owned by pro-Japanese collaborators remained contested.

The Soviet Occupation and North Korea (1945–1948)

The Soviet occupation of north Korea was far more thoroughgoing in terms of state transformation. Soviet forces under General Ivan Chistyakov moved rapidly to establish control and implement Soviet-style institutional reform:

Land Redistribution and Social Revolution

The Soviets redistributed land seized from Japanese settlers and pro-Japanese Korean landlords to poor peasants, essentially carrying out an agrarian revolution. This was vastly more radical than anything attempted in the American south and garnered initial support from North Korean peasantry.

Industrial Nationalization

Large industrial enterprises, previously owned by Japanese zaibatsu and Korean collaborators, were nationalized and placed under Soviet or Soviet-backed Korean administration. The north’s industrial base — coal mines, textile factories, chemical plants — was reorganized on Soviet lines.

Political Tutelage

The Soviets, like the Americans, initially intended their occupation as temporary. However, Soviet strategy rapidly shifted toward consolidating communist control of the north. The Soviets cultivated and elevated Kim Il-sung (김일성; 1912–1994), a communist guerrilla fighter who had fought against Japanese forces in Manchuria and had Soviet military training. Kim Il-sung, though barely known in Korea proper during the colonial era, was promoted by the Soviets as a nationalist hero and put at the head of a Soviet-sponsored administration.

Kim Il-sung’s background included fighting with anti-Japanese guerrilla forces in Manchuria in the 1930s and early 1940s. He was selected by Soviet commanders, over other Korean communist factions, as a suitable leader — young, militarily experienced, and malleable to Soviet direction. The Soviets also cultivated other Korean communists, including those with experience in the Soviet Union itself.

The Soviets sponsored the formation of the Korean Communist Party (조선공산당) and organized mass political rallies and organizations in the north to build support for communist governance. Soviet advisors and military officers remained present, but the nominal authority was vested in Korean figures.

Korean Political Movements and Leadership Factions

The Korean Provisional Government

During the colonial era, Korean nationalist exiles had established a Korean Provisional Government (대한민국임시정부) in Shanghai (1919), moving later to Chongqing. This government-in-exile, led by figures like Syngman Rhee and Kim Ku, claimed to represent Korean sovereignty and had nominal diplomatic recognition from China. When Korea was liberated in 1945, representatives of the Provisional Government attempted to return and claim authority.

However, the returning Provisional Government figures found themselves politically isolated. They were anti-communist, but they lacked an armed force or mass organization comparable to the Soviets’ backing of Kim Il-sung or the Americans’ military administration. The Provisional Government’s authority was never fully recognized by either occupation power.

Leftist and Communist Movements

Korean leftists and communists, who had organized during the colonial era (often underground or in exile in Manchuria and the Soviet Union), emerged as a significant political force in 1945. In the north, Soviet occupation and patronage gave communists overwhelming organizational advantage. In the south, leftist and communist organizations also formed and attempted to establish councils and committees to challenge the military government.

The American military government viewed leftist organizing with deep suspicion, fearing communist subversion. Labor unions, peasant organizations, and communist cells were targeted and suppressed. This anticommunist stance of the occupation amplified Korean perceptions that America was preventing genuine Korean independence and self-determination.

Conservative and Nationalist Factions

Conservative Korean figures, many with pre-colonial yangban or early-modern Japanese-era establishment credentials, also organized. Syngman Rhee (이승만; 1875–1965), an elder statesman with a doctorate from Princeton, American Protestant Christianity, and diplomatic experience, emerged as a conservative leader supported by the American military government. Rhee had lived in exile in the United States during the colonial era and represented continuity with pre-colonial Korean sovereignty and anti-Japanese nationalism, but from a conservative, pro-American perspective.

Kim Ku (김구; 1876–1949), another nationalist and Provisional Government leader, represented a more left-nationalist stance, favoring rapid independence and neutrality between great powers. Kim Ku, despite his non-communist ideology, opposed trusteeship and foreign occupation and sought Korean sovereignty.

Attempted Unification Talks and Failed Diplomacy (1945–1947)

The Moscow Agreement (December 1945)

The Foreign Ministers’ Conference in Moscow (December 1945) addressed Korea’s future. The United States, Soviet Union, and Britain agreed that Korea would eventually be reunified but only after a period of international “trusteeship.” This trusteeship arrangement — whereby a temporary multinational authority would prepare Korea for independence — was intended to prevent either superpower from monopolizing control and to build Korean political capacity for self-governance.

However, Korean nationalists across the political spectrum fiercely opposed the trusteeship concept, viewing it as a continuation of foreign domination. Anti-trusteeship sentiment united otherwise divided Korean factions: leftists, conservatives, and nationalists all opposed the idea. The Moscow Agreement became deeply unpopular in Korea.

Joint Soviet-American Commission

A Joint Soviet-American Commission was established to work toward Korean unification and a schedule for independence. However, the commission proved deadlocked over fundamental issues: What political system would unified Korea adopt? Would it be communist (Soviet preference) or anti-communist (American preference)? Would elections be held? Would existing people’s committees (소비에트-style councils organized in the north) be recognized?

By 1947, it was clear that Soviet and American occupation officials could not agree on Korea’s future. The commission effectively gave up; no progress was made on reunification.

Violence and Suppression in the South (1946–1948)

The political struggle in the American-occupied south was not merely procedural. It was accompanied by organized state violence against leftists, labor organizers, and perceived sympathizers with the north, and by popular uprisings that the military government and Korean police suppressed with lethal force.

The Autumn Uprising (1946)

In October 1946, a general strike and popular uprising erupted across multiple southern provinces, beginning with railroad workers in Daegu and spreading rapidly. The uprising — known in Korean historiography as the Daegu Autumn Uprising (10월 항쟁) — reflected mass grievances over food shortages, the preservation of the colonial police, and the American military government’s alignment with Korean conservatives. Korean police and American military forces suppressed the uprising; estimates of deaths range from several hundred to over a thousand, with thousands arrested.

The Jeju April 3 Uprising and Massacre (1948–1954)

The most consequential internal violence of the founding period occurred on Jeju Island. Tensions between Jeju’s population — historically distinct in dialect, culture, and economic interests from the mainland — and the mainland-based police (staffed heavily by ex-colonial collaborators) had been building since 1946. The Jeju branch of the South Korean Labor Party (Korean Communist Party) organized resistance to the May 1948 election, viewing it as a step toward permanent division.

On April 3, 1948, the Jeju April 3 Uprising (제주 4·3 사건) began when leftist guerrillas and local villagers attacked police stations across the island. The Syngman Rhee government and American occupation authorities responded with a brutal military campaign. For nearly six years (1948–1954), military and police forces pursued a scorched-earth strategy: burning villages, executing suspected sympathizers (often with little or no evidence), and imprisoning tens of thousands.

The toll was catastrophic. By most scholarly estimates, between 14,000 and 30,000 Jeju residents were killed — roughly 10–25 percent of the island’s population — with the worst violence concentrated in 1948–1949. Entire villages were razed; survivors fled to the hills or were herded into detention camps. The massacre was politically suppressed for decades by successive South Korean governments; survivors and their descendants faced discrimination and state surveillance into the 1990s.

Only in 2000, under President Kim Dae-jung, did the South Korean government formally acknowledge the massacre and begin compensating victims’ families. In 2003, President Roh Moo-hyun issued a formal state apology — the first by a sitting South Korean president — recognizing that the killings constituted a grave injustice by the state against the Korean people. See Roh Moo-hyun and Kim Dae-jung.

The Yeosu-Suncheon Rebellion (October 1948)

In October 1948, units of the South Korean Army’s 14th Regiment, stationed in Yeosu (여수), South Jeolla Province, mutinied rather than deploy to Jeju to suppress the uprising there. On October 19, 1948, rebels seized Yeosu and the neighboring city of Suncheon (순천), proclaiming allegiance to the Korean Labor Party (South Korean communist organization). Government forces retook the cities within weeks; the Rhee government conducted mass executions of soldiers, civilians, and suspects in the region.

The Yeosu-Suncheon Rebellion (여순 사건) reinforced Rhee’s anticommunism and accelerated the consolidation of state violence. Military and police units conducted “screening” operations across southern provinces, arresting or executing suspected leftists by the thousands. The episode demonstrated both the depth of leftist sentiment in the Korean countryside and the ferocity of the state’s response.

The National Security Law (December 1948)

In December 1948, just months after the ROK’s founding, the National Assembly passed the National Security Law (국가보안법, NSL). The law criminalized:

• Membership in or support for any organization deemed anti-state (effectively, any communist or leftist organization)
• “Praises and encouragement” of anti-state activities
• Communication with North Korea or its representatives

The National Security Law became the legal backbone of anticommunist repression for the next half-century. Tens of thousands of South Koreans were arrested, tortured, and imprisoned under the NSL during the Rhee and subsequent authoritarian governments. The law remains in force today (though amended), and its continued existence is a subject of ongoing debate in South Korea’s legal and political community.

The Transition to Separate States (1947–1948)

By 1947, the United States and Soviet Union accepted that Korean division would persist and that separate governments would be established in each zone.

The United Nations and the South Korean Election (1947–1948)

The United Nations General Assembly, at American request, established the UN Temporary Commission on Korea (UNTCOK) to oversee elections in Korea and establish a Korean government. The Soviets refused to cooperate; UNTCOK could only operate in the south.

The South Korean election of May 10, 1948 was held in the American occupation zone with UNTCOK observation. The election was meant to choose a National Assembly that would draft a constitution for a new South Korean state.

The election was contested and incomplete:

• The election was held only in the south, making it a south-Korean-only exercise, not a Korea-wide unification vote.
• The American military government and conservative Korean figures aligned with Syngman Rhee favored the election; leftist and many nationalist figures opposed it as insufficient to achieve true independence.
• Voter turnout was significant but not universal; some constituencies saw low participation due to leftist boycotts or rightist violence.
• The resulting National Assembly (제헌국회) had a conservative/right-nationalist majority aligned with Syngman Rhee and American occupation interests.

The South Korean Constitution (July 1948) and Founding (August 15, 1948)

The elected National Assembly drafted and adopted a constitution for a new Korean state. The Constitution of the Republic of Korea, promulgated on July 17, 1948, established:

• A presidential system with a directly elected president and a unicameral national assembly
• Anti-communist articles declaring communism and pro-communist political activity illegal
• A mixed economy acknowledging private property while allowing state intervention
• Separation of powers with checks and balances (though with a powerful executive)

On August 15, 1948 — exactly 3 years after liberation from Japan — the Republic of Korea (대한민국, Daehan Minguk) was formally proclaimed. Syngman Rhee was elected president by the National Assembly on July 20, 1948, and inaugurated as the first president of the republic.

The founding of the ROK was celebrated as liberation and independence, though many Korean progressives and nationalists viewed it as incomplete: Korea remained divided, foreign occupation continued, and the new state’s dependence on American military and economic support was total.

The Parallel Founding of North Korea (September 1948)

In September 1948, just weeks after the ROK’s founding, the Soviets formally established the Democratic People’s Republic of Korea (조선민주주의인민공화국, Joseon Minjujuui Inmin Gonghwaguk, or DPRK) in the north. Kim Il-sung became the premier of this state, which adopted a Soviet-style socialist constitution.

The establishment of two separate Korean states, each claiming to represent all of Korea, crystallized the division.

The Syngman Rhee Era and South Korean Consolidation (1948–1950)

Syngman Rhee, the first president of the Republic of Korea, was an elder statesman of Korean independence. His credentials included:

• American education — a doctorate from Princeton and years lived in the United States
• Protestant Christianity — Rhee was a devout Christian, which aligned him with American missionaries and Korea’s growing Protestant community
• Provisional Government service — nominal roles in the Korean Provisional Government in exile
• Authoritarianism — Rhee had little enthusiasm for genuine democracy; he believed strong executive authority was necessary for national consolidation

Rhee’s presidency (1948–1960) was characterized by:

• Anticommunist consolidation — suppression of leftist organizations, labor unions, and political dissidents
• Land reform — eventual implementation of agricultural land redistribution, reducing the power of the traditional yangban landlord class
• American dependency — reliance on American military and economic aid; the U.S. occupation formally ended in 1948, but American military presence and aid remained central
• Nationalist rhetoric — appeals to Korean sovereignty and independence, while simultaneously depending on American patronage
• Authoritarian governance — suppression of press freedom, political opposition, and civil liberties in the name of national security

Rhee’s early years were marked by political instability, factional conflict, and the grinding suppression of communist and leftist organizing. Police and military forces — many of which were composed of former Japanese colonial police and military — carried out campaigns against suspected communists and leftists.

The security situation in South Korea was tense: North Korea, under Soviet patronage and with Soviet and Chinese military support, appeared to threaten invasion. Rhee framed South Korean politics around military readiness and anticommunism.

The Broader Legacy and Path Dependency

The liberation-and-founding period (1945–1948) established the conditions for the subsequent Korean War (1950–1953) and for the division of Korea that persisted through the Cold War.

What Was Lost and What Might Have Been

Contemporaries and later historians have debated whether Korean reunification was possible during this period, had different decisions been made. Some scholars argue that:

• A more genuine Korean self-determination process, free from Soviet and American occupation, might have led to a negotiated Korean governance structure
• Deeper land reform and social revolution in the south (as occurred in the north) might have addressed inequalities and reduced the appeal of communism
• A more Korean-led rather than occupation-led process might have produced a more legitimate state
• Soviet and American commitment to leaving Korea might have enabled Korean leaders to negotiate a unified structure

Others argue that Soviet and American Cold War imperatives made division inevitable; that Korean political leaders were too divided ideologically for self-governance; or that North Korea’s Sovietization meant southern non-alignment was impossible.

The Institutional Foundations

What is clear is that the political and institutional choices made in 1945–1948 shaped everything that followed:

• The 38th parallel division became permanent
• Syngman Rhee’s anti-communist, pro-American, authoritarian state model became the template for South Korean governance (though later presidents varied the specifics)
• Kim Il-sung’s Soviet-backed communist state became the template for North Korea
• The two Korean states emerged as Cold War antagonists, guaranteeing military confrontation

Related

• Japanese Colonial Period — the colonial era preceding liberation
• Korean War — the armed conflict that erupted two years after the founding, rooted in the liberation-and-founding divisions
• Korean Independence Movement — the anti-colonial struggle that preceded liberation
• Democratization of South Korea — South Korea’s long path from Rhee’s authoritarianism to democracy (1960–1993)
• South Korea–North Korea Relations and Inter-Korean Diplomacy — the ongoing consequences of division
• Government Structure of South Korea — the constitutional framework established in this period
• Park Chung-hee — the military leader who came to power after Rhee, fundamentally reshaping South Korea
• Kim Dae-jung — the first opposition-party president (1998–2003), who began formal acknowledgment of the Jeju massacre
• Roh Moo-hyun — the first president born after liberation (1946), who issued a formal state apology for the Jeju April 3 massacre and inherited the legacy of this founding era
• Incheon — the port where American occupation forces landed in September 1945, shaping the south’s political administration