Operation Courageous was a military operation performed by the United States Army during the Korean War designed to trap large numbers of Chinese and North Korean troops between the Han and Imjin Rivers north of Seoul, opposite the South Korean I Corps. The intent of Operation Courageous was for I Corps, which was composed of the U.S. 25th and 3rd Infantry Divisions and the Republic Of Korea (ROK) 1st Infantry Division, to advance quickly on the North Korean and Chinese troops and reach the Imjin River with all possible speed.
As a first step in the attempt to block and attack the North Korean I Corps, Ridgway on 21 March ordered his own I Corps to move forward to line Cairo, which he extended southwestward across General Milburn's zone through Uijongbu to the vicinity of Haengju on the Han. (Map 28) At points generally along this line six to ten miles north of line Lincoln Milburn's patrols had made some contact with the North Korean I Corps west of Uijongbu and the Chinese 26th Army to the east. Milburn was to occupy line Cairo on 22 March, a day ahead of the airborne landing at Munsan-ni, and wait for Ridgway's further order to continue north.1
Requiring Milburn to stand along line Cairo unless instructed to proceed stemmed from Ridgway's not yet having given the final green light to the airborne landing as of the 21st. Operation TOMAHAWK, as the landing was called, would take place only if Ridgway received assurances that weather conditions on 23 March would favor a parachute drop and that ground troops could link up with the airborne force within twenty-four hours. If these assurances were forthcoming, the 187th Airborne Regimental Combat Team, with the 2d and 4th Ranger Companies attached, was to drop in the Munsan-ni area on the morning of the 23d and block Route 1. Milburn was to establish physical contact with and assume control of the airborne force once it was on the ground. At the same time, he was to open a general corps advance toward line Aspen, which traced the lower bank of the Imjin River west and north of Munsan-ni, then sloped eastward across the corps zone to cut Routes 33 and 3 eight miles north of Uijongbu. Once on Aspen, Milburn was to expect Ridgway's order to continue to line Benton, the final COURAGEOUS objective line, some ten miles farther north. Reaching Benton would carry the I Corps virtually to the 38th parallel except in the west where the final line fell off to the southwest along the Imjin.