The Korean War may not have been quite as ugly as the Vietnam War, but it was pretty ugly. From James Bovard at fff.org:
This year is the 70th anniversary of the start of the Korean War, a conflict from which Washington policymakers learned nothing. Almost 40,000 American soldiers died in that conflict that should have permanently vaccinated the nation against the folly and evil of foreign intervention. Instead, the war was retroactively redefined. As Barack Obama declared in 2013, “That war was no tie. Korea was a victory.”
The war began with what Harry Truman claimed was a surprise invasion on June 25, 1950, by the North Korean army across the dividing line with South Korea that was devised after World War Two. But the U.S. government had ample warnings of the pending invasion. According to the late Justin Raimondo, founder of antiwar.com, the conflict actually started with a series of attacks by South Korean forces, aided by the U.S. military: “From 1945-1948, American forces aided [South Korean President Syngman] Rhee in a killing spree that claimed tens of thousands of victims: the counterinsurgency campaign took a high toll in Kwangju, and on the island of Cheju-do — where as many as 60,000 people were murdered by Rhee’s US-backed forces.”
The North Korean army quickly routed both South Korean and U.S. forces. A complete debacle was averted after Gen. Douglas MacArthur masterminded a landing of U.S. troops at Inchon. After he routed the North Korean forces, MacArthur was determined to continue pushing northward regardless of the danger of provoking a much broader war.
By the time the U.S. forces drove the North Korean army back across the border between the two Koreas, roughly 5,000 American troops had been killed. The Pentagon had plenty of warning that the Chinese would intervene if the U.S. Army pushed too close to the Chinese border. But the euphoria that erupted after Inchon blew away all common sense and drowned out the military voices who warned of a catastrophe. One U.S. Army colonel responded to a briefing on the Korea situation in Tokyo in 1950 by storming out and declaring, “They’re living in a goddamn dream land.”