As the division took over its new I Corps mission on 25 March, the Marine commander had one regiment of the 1st ROK Division attached as division reserve while his 5th Marines was still in the east. Operational plans originally had called for the 5th Marines, less a battalion, to locate in the Kimpo Peninsula area where it was anticipated Marine reserve units would be able to conduct extensive amphibious training. So overextended was the assigned battlefront position that General Selden realized this regiment would also be needed to man the line. He quickly alerted the 5th Marines commanding officer, Colonel Thomas A. Culhane, Jr., to deploy his regiment, then en route to western Korea, to take over a section of the JAMESTOWN front line instead of assuming reserve positions at Kimpo as originally assigned. General Selden believed that putting another regiment on the main line was essential to carrying out the division’s mission, to aggressively _defend_ JAMESTOWN Line, not merely to _delay_ a Communist advance. Only a few hours after the 5th Marines had begun its trans-Korea move, helicopters picked up Colonel Culhane, his battalion commanders, and key regimental staff officers and flew them to the relocated division command post (CP) in the west. Here, on 26 March, the regimental commander officially received the change in the 5th Marines mission. Following this briefing, 5th Marines officers reconnoitered the newly assigned area[15] while awaiting the arrival of their units. When the regiment arrived on the 28th, plans had been completed for it to relieve a part of the thinly-held 1st Marines line. On 29 March, the 5th Marines took over the center regimental sector while the 1st Marines, on the right regimental flank, compressed its ranks for a more solid defense. [15] Col Thomas A. Culhane, Jr. ltr to Hd, HistBr, G-3 Div, HQMC, dtd 16 Sep 59, hereafter _Culhane ltr_.