The Battle of Ongjin Peninsula () was a series of battles that occurred in Ongjin Peninsula between 25 and 26 June 1950 and was a part of the Operation Pokpung (North Korea) and Operation Western Region (South Korea) that marked the beginning of the Korean War. On 25 June, the Korean People's Army (KPA) 3rd 38-Guard Brigade, reinforced with the 1st Infantry Regiment of the 6th Infantry Division, launched a surprise attack on the Republic of Korea Army (ROKA) 17th Infantry Regiment in Ongjin Peninsula, modern-day Ongjin and Kangryong. The battle ended on 26 June with a KPA victory, but many ROKA troops were able to escape from the peninsula.
Prelude Ongjin Peninsula lies at the westernmost point of the 38th parallel. It is surrounded by the sea and can only be accessed by land through North Korean territory. Pupo, located at the southernmost point of the peninsula, was the only major supply line for the ROKA. To ensure a safe evacuation, securing Pupo was of utmost importance. The distance between Pupo and Incheon is 90 km by sea, and, at the time, it took 9 hours for a ferry to travel one way.
There are strategic mountains at the centre of the peninsula that can be used to observe the entire peninsula and be used for military encampments. Prior to the battle, the two opposing forces had already had three clashes near these mountains in 1949.
North Korea Between 10 and 23 June 1950, the KPA completed its deployment for full-scale war in the western region under the guise of military training. The KPA 3rd 38-Guard Brigade moved its seven battalions near Ongjin Peninsula and Yeonbaek (now Yonan) district. Meanwhile, the 1st Infantry Regiment and a Security Battalion located in Sariwon were separated from the 6th Infantry Division and moved to Chwiya to reinforce the 3rd Brigade. Their mission was to capture the entire Ongjin Peninsula and Yonan Peninsula while the higher command, I Corps, headed for Seoul.
To achieve the goal, the 3rd 38-Guard Brigade originally planned a full-out parallel attack with seven battalions and a regiment, keeping the 7th 38-Guard Battalion as a reserve unit. However, Brigadier General Choe Hyon, the commander of the 3rd Brigade, adjusted the plan right before the war instead of operating each unit independently to prevent the manpower on the frontline from getting too thin. The 1st Infantry Regiment was assigned to advance to Kangryong and split the ROK 17th Infantry Regiment in half.
The KPA troop strength in the region was 11,000, including 8,000 from the 3rd 38-Guard Brigade and 3,000 from attached units. They were armed with four M-30 howitzers, five SU-76M self-propelled guns, 32 ZiS-3 guns, 45 M-42 anti-tank guns, ninety-five 82-PM-41 mortars, sixteen 120-PM-43 mortars, and eight armoured vehicles.
Korean People's Army Ground Force 3rd 38-Guard Brigade - Brigadier General Choe Hyon (Ongjin Peninsula direction) - participants of the Battle of Ongjin Peninsula 2nd 38-Guard Battalion - (north of Ongjin) 4th 38-Guard Battalion - (north of Ongjin) 5th 38-Guard Battalion - (northwest of Ongjin) 6th 38-Guard Battalion - (northwest of Ongjin) 7th 38-Guard Battalion - (reserve) 1st Infantry Regiment (attached) - Colonel Kim Hu-chin (northeast of Ongjin) (Yonan Peninsula direction) - non-participant 1st 38-Guard Battalion - (north of Paechon) 3rd 38-Guard Battalion - (north of Yonan) (1) Security Battalion (attached) - (north of Chongdan)
South Korea The ROK 17th Infantry Regiment was tasked to defend a 45 km long border, which exceeded its capability by far—a division was normally tasked to cover 10 km. In addition, many higher mountains were located above the 38th parallel, creating a huge geographic disadvantage. Understanding the situation, the regiment commander Colonel Paik In-yup mobilised civilians to fortify bases on mountains below the 38th parallel, which were the only and the last major resistance line. Five civilians were killed by North Korean fire during the construction. The colonel also created a paramilitary force by combining several youth clubs to protect their hometowns.
The ROKA Headquarters had three defensive plans. The first was to hold the 38th parallel if the fighting was small-scale. The second was to hold the main resistance line until reinforcement arrived, if the battle was limited to the region. Lastly, if North Korea launched a full-scale war, then the regiment would retreat to Incheon from the port of Pupo while forcing the KPA to bleed as much as possible. The regiment and civilians conducted evacuation training for plans 1 and 2, but not plan 3. The military prioritised the families of military and civil servants, then allowed civilians as ship capacity allowed.
One month before the war, KPA artillery staff operations officer Major Kang Chang-nam and his liaison from the 3rd 38-Guard Brigade defected to the ROK 17th Regiment and provided information about the KPA battle orders, locations, and training status.
Paik ordered the adjustment of battalion positions to focus on the sector defended by the 3rd Infantry Battalion, which includes the road connecting Chwiya and Kangryong, to prevent the KPA from splitting the regiment. Moreover, he requested additional troops as recent North Korean activity indicated an additional KPA unit in the area.
On 20 June, many KPA vehicles and high-ranking officers were sighted on the frontline. On the night of 22 June, a line of vehicles was seen moving from Haeju to Chwiya with the headlights off. Despite these reports, at 24:00 on 23 June, the Army Headquarters lifted the special alert order that had been issued at the end of May, and allowed soldiers to take vacation or go out from the bases. Paik disobeyed the order. The next day, five United Nations observers visited the regiment and complained that the regiment was "creating tensions" and there was "no reason for a special alert", then went back to Seoul. As a result, Paik had to inevitably lift the emergency measures, except for the frontline troops, which ultimately weakened the defence line.
The 3rd Infantry Battalion guarded the regiment's right from the coast to Mt Noktal, and the 1st Infantry Battalion was protecting the left from Mt Noktal to Mt Turak. The 2nd Infantry Battalion acted as a reserve unit, mostly doing basic and tactical training near the regimental command at Ongjin Mine, located north of Ongjin.
The ROKA total troop strength in Ongjin Peninsula was 3,600, including 2,719 from the 7th Infantry Regiment, 526 from the 7th Artillery Battalion, 129 from the anti-tank company, and other supporting units. They were armed with 12 M3 howitzers, six M1 anti-tank guns, 12 M1 mortars, 18 M2 mortars, 60 M9A1 rocket launchers and 25 machine guns.
Republic of Korea Army 17th Infantry Regiment - Colonel Paik In-yup (HQ in Ongjin Mine) 1st Infantry Battalion - Major Kim Hui-tae (regiment left, HQ in Mahyon) 1st Company - Captain Gang Eun-deok (battalion reserve, HQ in Mahyon) 2nd Company - 1st Lieutenant Han Hyeok (Battalion left, HQ in Undong) 3rd Company - (Battalion right, HQ on Hill 429) 4th Company - 1st Lieutenant Son Chang-sul (weapon company) 2nd Infantry Battalion - Major Song Ho-rim (regiment reserve, HQ in Ongjin Mine) 5th Company - 1st Lieutenant Kim Gyo-seok 6th Company 7th Company 8th Company - (weapon company) 3rd Infantry Battalion - Major Oh Ik-gyeong (regiment right, HQ in Kangryong) 9th Company - 1st Lieutenant Han Hong (battalion centre, HQ on Mount Chak) 10th Company - Captain An Je-hui (battalion left, HQ on Mount Noktal) 11th Company - 1st Lieutenant Kim Jong-yun (battalion right, HQ in Uhyon) 12th Company - Captain Jeong Gyu-han (weapon company) 7th Artillery Battalion (attached) - Major Bak Jeong-ho 1st Battery - (attached to the regiment HQ) 2nd Battery - 1st Lieutenant Seo Jeong-seon (attached to the 3rd Battalion in Todong) 3rd Battery - 1st Lieutenant Kim Won-gil (attached to the 1st Battalion in Donggokdong) Anti-tank gun Company (attached) - Captain Noh Gyeong-eok (3 platoon, each platoon attached to the 1st & the 3rd Battalion and the regiment HQ) (1) engineer company (attached) - 1st Lieutenant Bak Jun-hui (attached to the regiment HQ)
Timeline On 25 June at 04:00, the KPA fired red and green flares and fired artillery on the ROK defences for 30 minutes. At 04:40, Major Kim Hui-tae, the commander of the ROK 1st Battalion, was informed that an enemy platoon was approaching through a blind spot by the 3rd Company. Kim decided to take care of the situation himself and headed towards Chadong (1.5 km north of Mahyon), in the vicinity of the 3rd Company HQ.
At 05:00, the ROK 7th Artillery Battalion received authorisation from American officer Major Frank Brown, who was part of the Korean Military Advisory Group (KMAG), to fire their M3 howitzers. However, the authorisation was given much later than requested due to KMAG's control over large-calibre weapons, which was aimed at preventing a preemptive strike by South Korea on North Korea and avoiding any escalation of the war involving the Soviet Union.
During the same period, the ROK 1st Platoon, 2nd Company lost its position to a KPA battalion. When Kim arrived at Chadong, he found that the 3rd Company HQ bunker had already been destroyed, and gun battles were taking place all around. He was also informed that the leader of the 2nd Platoon, 3rd Company 2nd Lieutenant Kim Ho-kyeong, had died. At 05:10, the ROK 1st Battalion lost communications with the 2nd and the 3rd Company.
At 05:30, Kim returned to Mahyon and ordered the battalion reserve, the 1st Company, to prepare to reinforce Chadong. He also requested assistance from the regiment HQ with the 2nd Battalion. At 05:40, KPA troops attacked the ROK 2nd Platoon, 2nd Company, but the platoon was able to repel the attack. However, the platoon noticed a North Korean flag being waved on Mount Turak, where the 3rd Platoon was located. A KPA battalion, led by cavalry, was also seen marching on the road to Ongjin without any opposition. The 2nd Platoon later joined the 2nd Battalion during the counterattack.
At 05:30, KPA artillery fire destroyed the ROK 3rd Battalion's observation post and communication systems. As a result, the battalion had to rely on the SCR-300 operated by the 9th Company. This caused confusion and limited command and control between units. Despite the situation, the ROK 3rd Battalion continued to fight against the KPA 1st Infantry Regiment in the fog along the 38th parallel. To help the situation, Paik sent an operations officer to the 3rd Battalion to hold positions and recover communications.
At the ROK 17th Infantry Regiment HQ, Paik was initially hesitant to send reinforcements to the 1st Battalion. He expected the main KPA offensive to come from the eastern front, and felt that the situation of the 3rd Battalion was more critical. However, he changed his mind after receiving a report at 06:10 about the death of Kim due to an 82-PM-41 mortar attack. Moreover, the defence of the 2nd Company, 1st Battalion started to crumble under the concentrated KPA fire, and the 3rd Company also suffered losses, including their commanding officer, and allowed the KPA to break through the defence line. As a result, Paik ordered the 2nd Battalion (excluding the 6th Company) to reinforce the 1st Battalion, and they moved out at 06:40.