June 25, 1950
The North Korean attack against the Ongjin Peninsula on the west coast, northwest of Sŏul, began about 0400 with a heavy artillery and mortar barrage and small arms fire delivered by the 14th Regiment of the NKPA 6th Division and the BC 3rd Brigade. The ground attack came half an hour later across the Parallel without armored support.
It struck the positions held by a battalion of the ROK 17th Regiment commanded by Col. Paik In Yup.
June 25, 1950 0900
The North Korean attack against the Ongjin Peninsula on the west coast, northwest of Sŏul, began about 0400 with a heavy artillery and mortar barrage and small arms fire delivered by the NKPA 14th Regiment of the NKPA 6th Division and the BC 3rd Brigade. The ground attack came half an hour later across the Parallel without armored support. It struck the positions held by a battalion of the ROK 17th Regiment commanded by Col. Paik In Yup. 
The first message from the vicinity of the Parallel received by the American Advisory Group in Sŏul came by radio about 0600 from five advisers with the ROK 17th Regiment on the Ongjin Peninsula. They reported the regiment was under heavy attack and about to be overrun. 
Before 0900 another message came from them requesting air evacuation. Two KMAG aviators, Maj. Lloyd Swink and Lt. Frank Brown, volunteered to fly their L-5 planes from Sŏul. They succeeded in bringing the five Americans out in a single trip. [03-16]
The Ongjin Peninsula, cut off by water from the rest of South Korea, never had been considered defensible in case of a North Korean attack. Before the day ended, plans previously made were executed to evacuate the ROK 17th Regiment. What was left, 2 battalions.
June 26, 1950
Two LST's from Inch'ŏn joined one already offshore, and on Monday, 26 June, they evacuated Col. Paik In Yup (17th Regiment, and most of two battalions-in all about 1,750 men. The other battalion was completely lost in the early fighting.
The 14th Regiment, 6th Division, turned over the Ongjin Peninsula area to security forces of the BC 3rd Brigade on the second day and immediately departed by way of Haeju and Kaesŏng to rejoin its division.
East of the Ongjin Peninsula, Kaesŏng, the ancient capital of Korea, lay two miles south of the Parallel on the main Sŏul-P'yŏngyang highway and railroad. Two battalions of the 12th Regiment, ROK 1st Division, held positions just north of the town. The other battalion of the regiment was at Yŏnan, the center of a rich rice-growing area some twenty miles westward.
The 13th Regiment held Korangp'o-ri, fifteen air miles east of Kaesŏng above the Imjin River, and the river crossing below the city. The 11th Regiment, of the 1st Division in reserve, and division headquarters were at Suisak, a small village and cantonment area a few miles north of Sŏul. Lt. Col. Lloyd H. Rockwell, senior adviser to the ROK 1st Division, and its youthful commander, Col. Paik Sun Yup, had decided some time earlier that the only defense line the division could hold in case of attack was south of the Imjin River.
Songak-san (Hill 475), a mountain shaped like a capital T with its stem running east-west, dominated Kaesŏng which lay two miles to the south of it. The 38th Parallel ran almost exactly along the crest of Songak-san, which the North Koreans had long since seized and fortified. In Kaesŏng the northbound main rail line linking Sŏul-P'yŏngyang-Manchuria turned west for six miles and then, short of the Yesŏng River, bent north again across the Parallel.