Battle of Ongjin Peninsula

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 Ground Force (KPAGF) 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 ROKs were able to escape from the peninsula.

Prelude
Ongjin Peninsula lies at the westernmost of the 38th parallel. It is surrounded by the sea and can be accessed by land through North Korean territory. Pupo, located at the southernmost of the peninsula, was the only major supply line for the ROK. To ensure a safe evacuation, securing Pupo is of utmost importance. The distance between Pupo and Incheon is 90 km by sea, and it took 9 hours for a ferry to travel one way.

There are strategic mountains at the center of the peninsula that can observe the entire peninsula and use for military encampments. Prior to the battle, the two opposing forces already had three clashes near these mountains in 1949.

North Korea
Between 10 and 23 June 1950, the Korean People's Army (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 7 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, the I Corp, headed for Seoul.

To achieve the goal, the 3rd 38-Guard Brigade originally planned a full out parallel attack with 7 battalions and a regiment, and 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 as the manpower on the frontline may get too thin. The 1st Infantry Regiment was assigned to advance to Kangryong and split the ROK 17th Infantry Regiment in half.

The KPA total 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 4 M-30 howitzers, 5 SU-76M self-propelled guns, 32 M1927 guns, 45 M-42 anti-tank guns, ninety-five 82-PM-41 mortars, sixteen 120-PM-43 mortars, and 8 armored 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
 * 2th 38-Guard Battalion - (at north of Ongjin)
 * 4th 38-Guard Battalion - (at north of Ongjin)
 * 5th 38-Guard Battalion - (at northwest of Ongjin)
 * 6th 38-Guard Battalion - (at northwest of Ongjin)
 * 7th 38-Guard Battalion - (reserve)
 * 1st Infantry Regiment (attached) - Colonel Kim Hu-chin (at northeast of Ongjin)
 * (Yonan Peninsula direction) - non-participant
 * 1st 38-Guard Battalion - (at north of Paechon)
 * 3rd 38-Guard Battalion - (at north of Yonan)
 * (1) Security Battalion (attached) - (at 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, thus created huge geological disadvantage to the regiment to set up defense line. Understanding the situation, the regiment commander Colonel Paik In-yup mobilized civilians for fortifying bases on mountains below the 38th parallel, which were the only and the last major resistance line. In return, the military provided medical and public assistances to public. 5 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 ROK Army Headquarters had three defensive plans. The first was to hold the 38th parallel if the fights are small-scale. The second was to hold the main resistance line until reinforcement arrives, if the battle is limited to the region. Lastly, if North Korea launches 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 the plan 1 and 2, but not the plan 3. The military prioritized families of military and civil servants, then civilians until ships capacity allows.

One month before the war, a 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.

Colonel Paik ordered to adjust 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, the colonel requested for additional troops as recent North Korean activity made the regiment to judge existence of an additional KPA unit in the area.

Since 20 June, many KPA vehicles and high-ranking officers have been sighted on the frontline. On the night of 22 June, a line of vehicles was identified moving from Haeju to Chwiya with the headlights off. 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 vacations or go out from the bases. Colonel Paik disobeyed the order because it was total nonsense. On the next day, five United Nations servicemen visited the regiment and complained that the regiment was "creating tensions" and told "no reason for special alert" and 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 defense 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 ROK 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, 6 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 center, 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 defenses for 30 minutes. At 04:40, Maj 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. Maj 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 authorization from American officer Maj Frank Brown, who was part of the Korean Military Advisory Group (KMAG), to fire their M3 howitzers. However, the authorization was given much later than requested due to KMAG's control over large-caliber 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 time period, the ROK 1st Platoon, 2nd Company lost its position by a KPA battalion. When Maj 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 Lt Kim Ho-kyeong, had died. At 05:10, the ROK 1st Battalion lost communications with the 2nd and the 3rd Company.

At 05:30, Maj 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, the 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 waving on Mount Turak, where the 3rd Platoon was located. A KPA battalion, led by cavalries, was also seen marching on the road to Ongjin without any opposition. The 2nd Platoon later joined the 2nd Battalion during the counterattack.

At 5:30, the 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, Col Paik sent an operations officer to the 3rd Battalion to hold positions and recover communications.

At the ROK 17th Infantry Regiment HQ, Colonel 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 Maj Kim due to an 82-PM-41 mortar attack. Moreover, the defense 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 defense line. As a result, Col Paik ordered the 2nd Battalion (excluding the 6th Company) to reinforce the 1st Battalion, and they moved out at 06:40.

The ROK 2nd Battalion hurried to Mahyon (4 km north of Ongjin), where the 1st Battalion HQ was located. Upon arrival, they found a 38-Guard Battalion causing chaos in the empty compound by setting fire to everything. At 07:00, the 2nd battalion joined forces with units of the 4th Company and the 3rd Battery. The battalion commander Maj Song Ho-rim ordered the battalion to encircle the KPA by positioning the 5th Company on the right and the 7th Company on the left. They fired shots from 17 heavy guns, including 10 M1 mortars, 2 M1 anti-tank guns, and 5 M3 howitzers. The attack caused panic among the KPA, and the ROK took control of the situation.

However, at 09:00, Col Paik ordered the 2nd Battalion to redirect a company to assist the 3rd Battalion due to the critical situation at the regiment's right defense. Maj Song did not want to reduce the manpower and lose the momentum of the counterattack, so he sent a mortar platoon of the 8th Company and the 3rd Battery to join with the 6th Company, which was the last reserve of the regiment, to help the 3rd Battalion.

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. The KPA's guns began firing, forcing the ROK to abandon their positions and retreat to the south. At 08:00, the ROK 3rd Battalion CO, Maj Oh Ik-gyeong, met with 1st Lt Jo, the operations officer whom Col Paik had sent earlier, and sent Jo back to the regiment HQ to request reinforcement. To halt the KPA's advance, Maj Oh set up defenses on high grounds and mountains near the roads north of Kangryong that the KPA would march through, and instructed his men to prioritize targeting the armored vehicles.

Meanwhile, the ROK 1st Company, 1st Battalion led by Cpt Gang Eun-deok arrived and operated at Chadong since 07:30. However, as the haze disappeared on the battlefield, they discovered that they were surrounded by the KPA. The company was pinned down and fought for two hours until the ROK 5th Company arrived to rescue them. The 1st Company then joined the counterattack under the command of Maj Song. At 10:00, Maj Song received a gunshot wound on his left ear that barely missed his left face. Col Paik reported the urgency of the situation to the Army HQ and requested assistance. However, the HQ instructed the colonel to "defeat the enemy and withdraw through the land". At 10:35, two L-5s carrying five members of the KMAG arrived in Ongjin, and the pilots, Maj Lloyd Swink and 1st Lt Brown, informed Col Paik about the full-scale invasion by the KPA across the border.

At 10:40, the ROK 10th Company, 3rd Battalion at the west ridge of Mount Chima engaged with the KPA 1st Regiment. Although they managed to destroy 1 armored vehicle, they were forced to retreat due to the KPA's superior firepower. At 11:00, the ROK 9th Company stationed at Hill 200 carried out an ambush on the 1st Regiment. During the attack, the ROK killed several KPA soldiers and also damaged one SU-76M while destroying 2 armored vehicles with the help of six M9A1 rocket launchers. However, the ROK also suffered many losses, and eventually retreated to Kangryong.

At 11:00, Colonel Paik gave an order to relocate the regiment HQ to Kangryong and evacuate civilians. He also instructed that confidential documents, supplies, and facilities be destroyed due to the absence of any potential help. The streets were congested with wounded soldiers and evacuees, and the field hospital was struggling to manage. The Colonel arranged for five 2.5-ton trucks to transport the wounded, giving priority to soldiers with severe injuries. However, only the first round of transport was able to leave for Kangryong since the KPA zone of control had expanded. The other group of wounded soldiers had to make their way out themselves in order to survive. At 14:00, 1st Lt 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. They drove to Sagot (13 km south of Ongjin) and then landed at Pupo at 21:00 via a civilian boat carrying refugees.

At 11:30, the ROK 11th Company began to retreat after being attacked by KPA SU-76Ms.

At 14:00, the KPA 1st Regiment successfully broke through the defense line of the ROK 3rd Battalion and started advancing towards Kangryong. Col Paik made decision to relocate thee regiment HQ to Pupo because Kangryong was not an ideal location for defense. It was situated on a plain that would leave the ROK exposed to KPA attacks. Consequently, the colonel ordered all ROK in Kangryong sector, except for four M1 anti-tank guns and their gunners and assistant gunners, to establish a defense line between Chunggidong and Chukkyori (8 km southeast of Kangryong). The colonel 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.

At the time the order for retreat was given to the ROK 2nd Battalion, the 5th Company had already advanced to Chadong and the 7th Company had reached Sadong. Maj Song was angered by the order, as his battalion was winning and his soldiers had highly motivated. However, at 14:30, after assessing the situation, Maj Song issued retreat order to every unit under the 1st and the 2nd Battalion and instructed the 5th Company to create a path for withdrawal. The 5th Company successfully reached Mahyon by 15:00, and then the company leader 1st Lt Kim appointed a senior officer as the commanding officer before separating from the company with the 2nd Platoon leader and 18 others on a 2.5-ton truck. Upon reaching the field hospital, a civilian attempted to stop the truck but was disregarded. The truck was ambushed by the KPA, and killed five ROKs including 1st Lt Kim, but 15 ROKs survived. After the attack, the survivors fled to Yeonpyeong Island on a fishing boat. The remaining platoons of the 5th Company later joined the 3rd Battalion at Chunggidong by moving along the coastal line at 20:00. On the 25th the 5th Company reported 300 KPA casualties, as well as 20 KIA, including the company CO and the 3rd Platoon leader 1st Lt Lee Chun-man, and 30 WIA.

During the retreat, the 7th Company was assigned to guard the rear while other units of the 1st and the 2nd Battalion retreated. The 7th Company assigned the 1st Platoon to act as a rearguard, and began to pull out their units one at a time in the following order: the 8th Company, the machine gun platoon, the weapons platoon, the 2nd Platoon, the 3rd Platoon, and finally the 1st Platoon. However, the KPA attacked during the withdrawal of the 3rd Platoon, resulting in the loss of their leader 2nd Lt Kim Gyo-seok, and platoon sergeant Sgt 1st Class Go Yong-chul. Two platoons were separated from the company and had to make their way to the rally point at Naengjongri before moving on to Sagot.

Initially, Maj Song attempted to withdraw to Gangryong by breaking through KPA-occupied Yangwon, which was guarded by four SU-76Ms. At around 15:00, his troops went back to Mahyon after failing to destroy self-propelled guns with the M1 mortars. However, on their way back, they encountered KPA gunfire that almost killed the major. Therefore, he decided to go to Naengjongri and started reorganizing the troops gathered there, which were around 400 in number.

While the ROK forces in the western sector were regrouping, a group of four KPA SU-76Ms was heading towards Gangryong. However, the KPA column halted at the entrance of Gangryong to take extra caution due to previous ROK ambushes with anti-tank weapons. This decision gave an advantage to the ROK as the SU-76Ms became stationary and exposed side armor to the line of sight of the anti-tank guns commanded by Col Paik (most of the ROK munitions for the M1 anti-tank gun were high-explosives). The ROK destroyed three SU-76Ms and two armored vehicles, and escaping KPA crews were then targeted by a .50 Cal machine gun mounted on the colonel's ¾-ton vehicle. After that, the ROK anti-tank team then withdrew to Chunggidong safely. At 16:00, Col Paik started giving out detailed plans.

Despite Col Paik's attempts to contact the 2nd Battalion to order a withdrawal to Sagot, there was no response from the radio transceiver. Meanwhile, Maj Song and his foot soldiers were moving around Ongjin city, as KPA activity had been reported in the area. Part of his force consisted of a convoy of seven 2.5-ton trucks carrying combat troops (5), wounded (1) and ammunition (1). They drove through the city streets at high speed, firing at the KPA in the process. The convoy continued south and dismounted troops to secure the three-way interaction next to Mount Yongun (3 km south of Ongjin) to provide cover for the retreating ROK to Sagot.

At 18:00, Maj Song was informed about the rescue plan and received instructions from Col Paik. By 19:30, approximately 700 ROKs had assembled near Mount Yongun, including the 1st and 3rd platoon of the 7th Company. Maj Song assigned the 7th Company and a weapon platoon of the 4th Company to the mount as the first rearguard and stationed the 1st Company at Yangmyongdong (2 km north of Sagot) as the second rearguard to provide cover for the first. Then, the major and the rest of the troops moved to Sagot.

In the eastern sector, several ROK units that had been scattered, including the 5th Company, around 100 soldiers from the 3rd Battalion, and the engineer company, made their way to the regiment at Pupo direction and joined them. In anticipation of a potential KPA attack that could lead to the collapse of his force, Col Paik decided to use deception. He ordered Maj Oh and Maj Bak to fire every howitzer and mortar until sunrise. He then instructed the transportation officer to use all 85 vehicles to continuously do roundtrips from Pupo to Chunggidong. 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. The deception worked and the KPA did not launch any attacks until the next morning.

Sagot was filled with soldiers, policemen, and refugees in chaos. Upon arrival, Maj Song fired a pistol in the air in an attempt to control the crow and threatened disobedient for possible execution. However, there were no ships available at the port. 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. Maj Song contacted the police station and redirected the mission to evacuate 1,300 ROKs and 700 policemen and civilians at Sagot. Therefore, the police chief sent out Daeseong to transport 80 people per roundtrip to Yongho Island. The ROK set fire to all of their 15 vehicles before leaving.

At 23:30, the Republic of Korea Navy (ROKN) ship LST-801 docked at Pupo. The Navy Capt Kim Ok-kyeong informed Col Paik that due to the tide, the ship must depart before 08:00. The colonel promptly left Pupo for the front line.

On 26 June at 00:30, Col Paik summoned Maj Oh and Maj Bak to withdraw one company at a time using vehicles with their headlights off. The withdrawal began at 01:00, and by 05:00, only the 11th Company, a battery, and an anti-tank gun company remained at the defense line when the KPA reopened artillery fire.

The 11th Company stopped using vehicles and retreated on foot under the covering fire from anti-tank guns and howitzers. However, two KPA SU-76Ms ignored incoming ROK fire and advanced to Chochon, stopping at a bridge that had been destroyed by ROK engineers earlier. The KPA mobilized civilians to repair the bridge and the KPA continued their advance three hours later. The ROK used this as an opportunity to pull out their last remaining troops and hid two anti-tank guns near the road entering Pupo. The 11th Company made a separate escape via fishing boats.

At 07:00 in Sagot, the ROK 1st Company boarded Daeseong after transporting other ROKs and policemen. However, due to increasing KPA shelling, the ROK had to leave 500 refugees behind in Sagot. Another 100 ROKs landed on Yongho Island by different boats. The ROKs on the island were provided with food for the first time since the war started. At 9:00, supply officer 1st Lt Bak Won-keun sailed out on Daeseong in an attempt to find more ships.

At 09:30, two KPA SU-76Ms were destroyed near Pupo by anti-tank guns commanded by Col Paik. When the colonel returned to Pupo, most ROKs escaped from the area, and only around 100 ROKs were waiting for their regiment commander to return. From 05:00, the LST-801 departed Pupo to avoid getting stranded and was joined by a training ship operated by the maritime university. The LST-801 continued evacuating ROK with four landing crafts and fishing boats. The colonel sent an information officer Cap Yu Chang-hun to direct the training ship to rescue the 1st and 2nd Battalion in Sagot.

At 10:30, the KPA started shelling Pupo, and Col Paik and Maj Bak returned fire with the last M3 howitzer waiting to be disassembled to provide cover. At 11:00, the colonel ordered the last remaining ship to leave without him and continuously fired the howitzer until the ship was far enough from the danger zone. They disassembled and dumped the howitzer in the ocean, and then the colonel attempted to commit suicide using his pistol but was stopped by Maj Bak. They left Pupo on a small boat that Maj Bak found and were picked up by a fishing boat after drifting on the ocean without any means of propulsion for a few hours.

At 14:00, the ROK training ship arrived near Sagot, and there were no signs of the ROK but only the KPA cavalries patrolling the area. The ship then changed the course to Incheon.

At 15:00, the ROK led by Maj Song in Yongho Island departed for Pupo on four ships that Daeseong brought to the island. They arrived near Pupo after four hours but changed the course after learning about the KPA occupation of Pupo from ten ROKs of the 3rd Battalion whom the ship picked up.

More ROKs either individually or by a group made their escape. The last known ROK group to depart Ongjin Peninsula was at 15:30 from Pupo.

At 16:00, the LST-801 carrying 1,200 ROK passengers set the course for Incheon after waiting for the regiment commander. They were commanded by Lt Col Kim Hui-jun during the absence of Col Paik and landed in Incheon at 04:00 on 27 June. Upon landing, attached troops were ordered to return to their original units and the remaining 700 ROKs of the 17th Regiment went to a new rally point at Yeongdeungpo.

At 19:00, Col Paik arrived at Yeongpyeong Island and worked on the defenses of the island with local guards. After a few hours, the ROKN ships JMS-302 and JMS-307, commanded by Lt Yeom Bong-saeng and Capt Baek Un-gi respectively, arrived and rescued the colonel and 41 ROKs. They left the island at 02:00 on 27 June, and landed at Incheon at 08:00. The colonel reported the situation to the Chief of Staff of the Army Chae Byong-duk and the Ministry of Defense Shin Song-mo at the Army HQ, and was given a new mission to provide security for the government's relocation to Daejeon.

The ROK convoy led by Maj Song arrived at Yeonpyeong Island at 07:00 on 27 June. They left the island at 20:00 in three groups, and the first and second group docked at the Port of Incheon at 06:00 on 28 June. They waited for the third group until 20:00 and boarded the ROKN ship YMS-513, commanded by Lt Bak Gyeong-cheol, and landed at Gunsan at 07:00 on 29 June to join the regiment by train. The third group landed at Incheon at 11:00 and arrived at Daejeon on 30 June with help from the police.

ROK assessment
The ROK 17th Infantry Regiment mobilized residents before the war to fortify defensive positions and organized local organizations into local defense units to cooperate with the military. Together with Col Paik's decision to stay alert, the ROK was able to minimize casualties during the beginning of the KPA invasion. The regiment operated two battalions at the frontline and one battalion as a reserve. Battalions were rotated every two months, and the 2nd Battalion was undergoing intensive training on both small and heavy firearms, which allowed the Battalion to succeed during the ROK counterattack.

The regiment was not large enough to cover the entire front line. 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. Watch towers and communication systems were prioritized by the KPA, and were destroyed at an early stage of the battle. The ROK moved artilleries to the front and used to provide fire support in close range, repelling KPA attacks and causing many KPA casualties. However, the ROK frequently experienced shortages of ammunition mostly due to communication problems between units and logistics. Lack of communication also disrupted cooperation between the units, and in particular, during withdrawal, caused a lot of losses. In addition, many lives and equipment were lost due to the delay in support from the Army HQ.

Colonel Paik did not anticipate a full-scale invasion of the KPA, but he preserved the 17th Regiment against a superior force. However, the colonel made a crucial error in using the reserve battalion by assisting the ROK left defense too early, thus letting the KPA 1st Infantry Regiment crush the ROK right defense quickly and split the ROK in half by advancing to Kangryong.

Propaganda issues
On 25 June, Choe Gi-deok, a reporter from Yonhap News Agency (not to be confused with the current Yonhap News Agency), returned from Ongjin Peninsula and told Col Kim Hyeon-su, the director of the Ministry of Defense media agency, that Colonel Paik In-yup said he "will advance to Haeju", and it was mistakenly translated to "advancing to Haeju" during the broadcast. According to Col Paik, he never said such a thing. On the other hand, reporter Choe had a record of arrest for sympathizing with and promoting communism and disrupting public order. Choe later claimed that he disputed with Col Kim over the detail, but the colonel left as it was to keep the ROK morale high. Regardless of the credibility, public media started producing fake news about ROK victories including the "capture of Haeju" between 27 and 28 June. However, propaganda confused commanders of the ROK to plan out tactics correctly, damaging the military rather than helping. In addition, these false reports were used to fortify North Korea's claim on South Korea's artillery attacks between 23 and 25 June, which never happened, and South Korea's responsibility for starting the war.