Operation Courageous was a military operation performed by the United Nations Command (UN) during the Korean War designed to trap large numbers of Chinese People's Volunteer Army (PVA) and Korean People's Army (KPA) troops between the Han and Imjin Rivers north of Seoul, opposite the Republic of Korea Army (ROKA) I Corps. The intent of Operation Courageous was for US I Corps, which was composed of the US 25th and 3rd Infantry Divisions and the ROKA 1st Infantry Division, to advance quickly on the PVA/KPA forces and reach the Imjin River with all possible speed.
Maneuvering
As Operation Ripper showed that the PVA/KPA forces were withdrawing north of Seoul, US Eighth Army commander General Matthew Ridgway planned to block and attack the retreat of KPA I Corps. On 21 March Ridgway ordered US I Corps to move forward to the Cairo Line, which he extended southwestward across General Frank W. Milburn's zone through Uijongbu (37°43′40″N 127°3′3″E / 37.72778°N 127.05083°E) to the vicinity of Haengju (37°37′49″N 126°46′11″E / 37.63028°N 126.76972°E) on the Han River. At points generally along this line 6–10 miles (9.7–16.1 km) to the north, Milburn's patrols had made some contact with KPA I Corps west of Uijongbu and the PVA 26th Army to the east. Milburn was to occupy the Cairo Line on 22 March, a day ahead of the airborne landing at Munsan-ni, and wait for Ridgway's further order to continue north.
Requiring Milburn to wait stemmed from Ridgway's not yet having given the final green light to the airborne landing, Operation Tomahawk, as of 21 March. Operation Tomahawk 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 24 hours. If these assurances were forthcoming, the 187th Airborne Regimental Combat Team (187th RCT), with the 2nd and 4th Ranger Companies attached, was to drop in the Munsan-ni area on the morning of 23 March 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 the Aspen Line, 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 8 miles (13 km) north of Uijongbu. Once on Aspen, Milburn was to expect Ridgway's order to continue to the Benton Line, the final Courageous objective line, some 10 miles (16 km) farther north. Reaching Benton would carry I Corps virtually to the 38th Parallel except in the west where the final line fell off to the southwest along the Imjin.
Because I Corps otherwise would have an open east flank when it moved to the Benton Line, Ridgway extended its line southeastward into the US IX Corps' zone, across the front of the 24th Division and about halfway across the front of the ROKA 6th Infantry Division to a juncture with the Cairo Line. When Ridgway ordered I Corps to Benton, General William M. Hoge was to send his western forces to the line to protect the I Corps' flank. Meanwhile, in concert with Milburn's drive to the Cairo and Aspen Lines, Hoge was to complete the occupation of his sector of the Cairo Line. Elsewhere along the army front, US X Corps and the ROKA III and I Corps remained under Ridgway's order of 18 March to reconnoiter the area between the Hwach'on Reservoir and the east coast. As yet, neither General Edward Almond's patrols nor those of the ROKA corps had moved that deeply into North Korean territory.
The three divisions of I Corps started towards the Cairo Line at 08:00 on 22 March. The ROKA 1st Infantry Division, advancing astride Route 1 in the west, overcame very light resistance and had troops on the phase line by noon. The ROKA 3rd Infantry Division astride Route 3 in the center and the US 25th Infantry Division on the right also met sporadic opposition, but moved slowly and ended the day considerably short of the line.
Meanwhile, Milburn assembled an armored task force in Seoul for a drive up Route 1 to make the initial contact with the 187th RCT, if and after it dropped on Munsan-ni. Building the force around the 6th Medium Tank Battalion, which was borrowed from the 24th Infantry Division of IX Corps, he added the 2nd Battalion, 7th Infantry Regiment; all but one battery of the 58th Armored Field Artillery Battalion from the 3rd Division; and from Corps' troops he supplied a battery of the 999th Armored Field Artillery Battalion and Company A, 14th Engineer Combat Battalion. He also included two bridgelaying Churchill tanks from the British 29th Brigade, which had recently been attached to I Corps. Lieutenant colonel John S. Growdon, commander of the 6th Medium Tank Battalion, was to lead the task force.
Ridgway made the final decision on the airborne operation late in the afternoon of 22 March during a conference at Eighth Army main headquarters in Taegu. General Earle E. Partridge, the Fifth Air Force commander, assured him that the weather would be satisfactory on the next day; Colonel Gilman C. Mudgett, the new Eighth Army G-3 operations officer, predicted that contact with the airborne unit would be made within a day's time, as Ridgway required, and also that the entire I Corps should be able to advance rapidly. Given these reports, Ridgway ordered the airborne landing to take place at 09:00 on the following day.
On hearing the final word on the Munsan-ni drop, Milburn directed Task Force Growdon to pass through the ROKA 1st Division on the Cairo Line early on 23 March and proceed via Route 1 to reach the airborne troops, while his three divisions were to resume their advance with the objective of reaching the Aspen Line. The ROKA 1st Division, which would be following Task Force Growdon, was to relieve the 187th RCT upon reaching Munsan-ni, and the airborne unit then was to prepare to move south and revert to Eighth Army reserve.
First attack
On 23 March, Task Force Growdon, which was completely motorized, passed through the ROKA 1st Division shortly after 07:00. No PVA/KPA forces opposed the armored column as it moved ahead of the ROKA, but within minutes the third tank in column hit a mine while bypassing a destroyed bridge at the small Changneung River. The task force was held up while engineers removed a dozen other mines from the bypass. Proceeding slowly from that point with a mine detector team leading the way afoot, Growdon's column moved only 1 mile (1.6 km) to the village of Sinwon-ni before encountering more mines. When the 187th RCT began landing at Munsan-ni at 09:00, Growdon's task force was stopped some 15 miles (24 km) to the south.
C-46 Commandos and C-119 Flying Boxcars of the 315th Air Division had begun lifting the airborne troops from the Taegu airfield shortly after 07:00, all heading initially for a rendezvous point over the Yellow Sea west of the objective area. The second serial of aircraft, with the 1st Battalion, 187th RCT aboard, was in flight only briefly before engine trouble in the lead plane forced the pilot to return to Taegu for a replacement aircraft. The combat team landed before the new lead plane, whose passengers included the 1st Battalion commander, could reach Munsan-ni. The drop, as a result, did not come off entirely as planned.
General Frank S. Bowen, commander of the 187th RCT, had designated two drop zones, one about 1 mile (1.6 km) northeast of Munsan-ni at 37°51′36″N 126°48′16″E / 37.86000°N 126.80444°E, another about 3 miles (4.8 km) southeast of town at 37°49′32″N 126°49′14″E / 37.82556°N 126.82056°E. The 1st Battalion was to land in the lower zone, the remainder in the one to the north. As planned, the 3rd Battalion with the 4th Ranger Company attached jumped first, Bowen having given it the mission of securing the northern drop zone. Bowen's plan went awry when the leaderless second serial of planes mistakenly followed the first and dropped the 1st Battalion also in the northern zone. The 2nd Battalion with the 2nd Ranger Company followed not long after, then the 674th Airborne Field Artillery Battalion, and at 10:00 the artillery heavy drop.
In the brief interval between the drops of the 1st and 2nd Battalions, Ridgway arrived by L-19, landing on a road between Munsan-ni and the northern drop zone. En route, he had flown over Task Force Growdon then held up at Sinwon-ni, a fact he passed to Bowen. Shortly after 10:00, Ridgway saw a single stick of paratroops jump from a plane over the lower drop zone. The replacement plane carrying the 1st Battalion commander and party had finally reached Munsan-ni, and its passengers had jumped in the correct zone not knowing that they would be the only troops in the area.
To the north, resistance in and immediately around the drop zone was minor and sporadic, amounting to a few small groups of KPA and a meager amount of fire from mortars located somewhere to the north. Overcrowding caused by the 1st Battalion's misdirected drop complicated the 3rd Battalion's assembly, but units managed to sort themselves out and secure the borders of the drop zone. An unexpected annoyance was created by civilians who appeared in the drop zone and began carrying away parachutes. Shots fired over their heads ended the attempted theft. Against moderate but scattered opposition the 2nd Battalion proceeded to occupy heights northeast of the drop zone, and under the command of its executive officer the 1st Battalion, less Company B, moved into the ground to the north and northwest, clearing Munsan-ni itself in the process.
Company B went on a rescue mission to the southern drop zone after learning that the command group of the 1st Battalion had come under fire on Hill 216 (37°50′18″N 126°48′27″E / 37.83833°N 126.80750°E) overlooking the drop zone from the northwest. Company B forced the PVA troops off the hill, allowing its survivors to withdraw to the southwest, and reached the drop zone by 15:00. The rescue force and the battalion command group arrived at the regimental position to the north about two hours later. By that time Bowen's forces had secured all assigned objectives.
Battle casualties among the airborne troops were light, totalling 19. Jump casualties were higher at 84, but almost half of these returned to duty immediately after treatment.
PVA/KPA casualties included 136 dead counted on the field and 149 taken captive. Estimated losses raised the total considerably higher. Prisoner interrogation indicated that the forces who had been in the objective area were from the KPA 36th Regiment, 19th Division and had numbered between 300-500. Most of the remainder of the KPA I Corps apparently had withdrawn above the Imjin well before the airborne landing.
Linkup
The point of Task Force Growdon reached Munsan-ni at 18:30 on 23 March, but the remainder of the extended column took several hours longer. The force encountered no PVA/KPA positions along Route 1 but was kept to an intermittent crawl by having to lift or explode over 150 live mines, some of them booby-trapped, and almost as many dummy mines, including a 5 miles (8.0 km) stretch of buried C-rations and beer cans. Casualties were few, but four tanks were disabled by mines. As the last of these tanks hit a mine 1 mile (1.6 km) below Munsan-ni, the explosion attracted artillery fire that damaged two more. The tail of the task force finally arrived at the airborne position at 07:00 on 24 March.
Milburn's orders to the 187th RCT for operations on 24 March called only for patrolling. Having been given control of Task Force Growdon by Milburn, Bowen built his principal patrols around Task Force Growdon's tanks and sent them to investigate ferry sites on the Imjin and to check Route 2Y, an earthen road running east from Munsan-ni, as far as the village of Sinch'ŏn, 10 miles (16 km) away. One patrol made contact while checking an Imjin ferry site and ford 10 miles (16 km) northeast of Munsan-ni. Six PVA were killed and twenty-two captured. The patrol suffered no casualties, but a tank had to be destroyed after it got bogged down at a stream crossing while approaching the lmjin. A few rounds of artillery fire meanwhile fell in the northern drop zone but caused no casualties.