[214] UN forces led by General Douglas MacArthur led the counterattack, scoring a stunning surprise victory with an amphibious landing at the Battle of Inchon that nearly trapped the invaders. UN forces marched north, toward the Yalu River boundary with China, with the goal of reuniting Korea under UN auspices.[215]
China surprised the UN forces with a large-scale invasion in November. The UN forces were forced back to below the 38th parallel, then recovered.[216] By early 1951 the war became a fierce stalemate at about the 38th parallel where it had begun. Truman rejected MacArthur's request to attack Chinese supply bases north of the Yalu, but MacArthur promoted his plan to Republican House leader Joseph Martin, who leaked it to the press. Truman was gravely concerned further escalation of the war might lead to open conflict with the Soviet Union, which was already supplying weapons and providing warplanes (with Korean markings and Soviet aircrew). Therefore, on April 11, 1951, Truman fired MacArthur from his commands.