The Battle of Ongjin Peninsula (Korean: 옹진반도 전투; Hanja: 甕津半島 戰鬪) 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.

[3] 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.

However, Brigadier general Choe Hyon, the commander of the 3rd Brigade, adjusted the plan right before the war instead of operating each unit independently as the manpower on the frontline may get too thin.

Understanding the situation, the regiment commander Colonel Paik In-yup mobilized civilians to fortify bases on mountains below the 38th parallel, which were the only and the last major resistance line.

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.

Despite all these reports, the Army Headquarters lifted the special alert order, which was issued at the end of May, on 24:00 23 June, and allowed soldiers to take vacation or go out from the bases.

As a result, Paik had to inevitably lift the emergency measures, except for the frontline troops, which ultimately weakened the defense line.

[1] 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.

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.

[3][1] At 05:00, the ROK 7th Artillery Battalion received authorization from American officer Major Frank Brown, who was part of the Korean Military Advisory Group (KMAG), to fire their M3 howitzers.

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.

[3][1] At dawn, soldiers and vehicles from the KPA 1st Infantry Regiment began advancing from Chwiya and moving towards Kangryong and Yangwon on the road, using the morning haze as cover.

Once the haze cleared, the ROK 3rd Battalion realized that the KPA had already advanced 2 km south of the 38th parallel, equipped with SU-76Ms, armored vehicles, and M-42 anti-tank guns.

At 10:35, two L-5s carrying five members of the KMAG arrived in Ongjin, and the pilots, Major Lloyd Swink and 1st Lieutenant Brown, informed Paik about the full-scale invasion by the KPA across the border.

During the attack, the ROKA killed several KPA soldiers and also damaged one SU-76M while destroying two armored vehicles with the help of six M9A1 rocket launchers.

At 14:00, 1st Lieutenant Seon U and 10 ROKs who were tasked to clean up the facilities escaped from the HQ with five 2.5-ton trucks fully loaded with 105 mm ammunition.

Paik also ordered the 1st and the 2nd Battalion to retreat, and sent anti-tank teams to set up the guns on the east side of the river that flows through the town.

However, at 14:30, after assessing the situation, Song issued retreat orders to every unit under the 1st and the 2nd Battalion and instructed the 5th Company to create a path for withdrawal.

However, the KPA column halted at the entrance of Gangryong to take extra caution due to previous ROKA ambushes with anti-tank weapons.

Additionally, the officer was instructed to turn off the headlights during the return trips, which would make the KPA believe that the ROK was receiving reinforcements from the mainland.

At 23:00, a senior inspector reported to the major that police on Yongho Island were unable to send their boat due to an ongoing mission.

However, two KPA SU-76Ms ignored incoming ROKA fire and advanced to Chochon, stopping at a bridge that had been destroyed by ROK engineers earlier.

The ROKA used this as an opportunity to pull out their last remaining troops and hid two anti-tank guns near the road entering Pupo.

Paik sent an information officer Captain Yu Chang-hun to direct the training ship to rescue the 1st and 2nd Battalion in Sagot.

[1] At 10:30, the KPA started shelling Pupo, and Paik and Bak returned fire with the last M3 howitzer waiting to be disassembled to provide cover.

Upon landing, attached troops were ordered to return to their original units and the remaining 700 ROKAs of the 17th Regiment went to a new rally point at Yeongdeungpo.

The ROK Army HQ also did not send any reinforcement despite hearing reports from the regiment including that from the defected KPA officer.

The regiment was unable to actively send out patrols due to a shortage of troops, thus allowing the KPA to break through the defense line without getting spotted.

Regardless of the credibility, public media started producing fake news about ROKA victories including the "capture of Haeju" between 27 and 28 June.