The Battle of Inchon was an amphibious invasion

Amphibious warfare

Amphibious warfare is the use of naval firepower, logistics and strategy to project military power ashore. In previous eras it stood as the primary method of delivering troops to non-contiguous enemy-held terrain...

 and battle of the Korean War

Korean War

The Korean War was a conventional war between South Korea, supported by the United Nations, and North Korea, supported by the People's Republic of China , with military material aid from the Soviet Union...

 that resulted in a decisive victory and strategic reversal in favor of the United Nations

United Nations

The United Nations is an international organization whose stated aims are facilitating cooperation in international law, international security, economic development, social progress, human rights, and achievement of world peace...

 (UN). The operation involved some 75,000 troops and 261 naval vessels, and led to the recapture of the South Korean capital Seoul

Seoul

Seoul , officially the Seoul Special City, is the capital and largest metropolis of South Korea. A megacity with a population of over 10 million, it is the largest city proper in the OECD developed world...

 two weeks later.

The battle began on September 15, 1950, and ended September 19. Through a surprise amphibious assault far from the Pusan Perimeter

Battle of Pusan Perimeter

The Battle of Pusan Perimeter was a large-scale battle between United Nations and North Korean forces lasting from August 4 – September 18, 1950. It was one of the first major engagements of the Korean War...

 that UN and South Korean forces were desperately defending, the largely undefended city of Incheon

Incheon

The Incheon Metropolitan City is located in northwestern South Korea. The city was home to just 4,700 people when Jemulpo port was built in 1883. Today 2.76 million people live in the city, making it Korea’s third most populous city after Seoul and Busan Metropolitan City...

 was secured after being bombed by UN forces.