Meanwhile, Captain Welby Cronk led Company D forward on the left of the highway against a strongly defended dike fronting the Kalchon’s western branch. Progress was slow and casualties severe, but the Marines closed to within 100 yards of the barrier by noon. There they dug in and slugged it out, while the 2d and 3d Platoons of Charlie Company tanks alternated in ripping the Communist trenches with 90mm, delayed-action shells. Heavy fighting continued on the right side of the road until evening. Companies E and F fought part way up the slopes of the ridge and suffered heavily during the close exchange with the Reds on the crest. Since the enemy was still in control of most of the high ground at dusk, Sutter ordered the assault units to withdraw into 2/1’s zone and dig in with Dog Company. VMF-214 covered the hot disengagement--one of the most difficult of all tactics--under a masterful job of forward air controlling by First Lieutenant Norman Vining, Sutter’s FAC. After bombing and rocketing from 75 to 100 yards beyond the Marine front, the Corsairs closed to within 30 yards for strafing runs to shield the retracting line of infantry.[355] [355] _Ibid._; and E. H. Giusti and K. W. Condit, “Marine Air Over Inchon-Seoul,” _Marine Corps Gazette_, 36, no. 6 (Jun 52). [Illustration: ASSAULT OF YONGDUNG-PO 1st MARINES----21 SEP] The seventh straight day in the assault had cost the 2d Battalion 11 killed and 74 wounded, bringing its total casualties since D-Day to 28 KIA and 226 WIA. Partially because of these crippling statistics, Colonel Puller, at 1530 on the 21st, had committed 3/1 to the relief of the battle-weary outfit. The reserve battalion swung northeast from Lookout Hill to flank the enemy dike positions facing Company D from the eastern tributary. Crossing the Kalchon against light resistance, the attackers ran into trouble at the fortified levees fronting southwestern Yongdongpo. After heavy machine guns of 3/1 bested a battery of Communist automatic weapons, Companies G and I, the latter on the right, attacked astride the stream branch. Progress was slow, but at a cost of 11 killed and 18 wounded, the Marines rolled up the heavily defended dike and reached the bridge entering the city. Darkness fell with the 3d Battalion entrenching to the north of the 2d, both units along the left side of the Inchon-Seoul Highway.[356] [356] 2/1 _SAR_; 3/1 _SAR_; LtCol T. L. Ridge ltr to CMC, 20 May 55; and LtCol E. H. Simmons ltr to CMC, 19 May 55.