At the time of the Han crossing, the general plan of the 1st Marine Division had been for RCT-5 to clear the north bank and open up crossing sites for RCT-1 in the Yongdungpo area. That regiment would then cross to seize South Mountain, just north of the crossing site, thus forming an enclave in Seoul proper. Further objectives were to be seized by RCT-1 to the north and east while the KMC Regiment passed through RCT-5 to attack the center of the city. Here a political motive entered the picture, since it was desired to have Koreans take a prominent part in the liberation of the former ROK capital. To the north, on the left flank of the Division, it was planned for RCT-7 to seize objectives to protect the flank and cut off the escape of the enemy. Meanwhile, RCT-5 would revert to Division reserve as soon as the tactical situation made it possible. So much for the plan. Before it could be put into execution, stiffening NKPA resistance made it necessary to consider revisions.[315] Not only was the hilly terrain northwest of Seoul well suited to defensive operations, but it had been a training area as far back as the Japanese overlordship, with fields of fire accurately charted. Moreover, it had become evident by the 21st that the enemy was about to exchange a strategy of delaying operations for one of defending to the last ditch. The 1st Marines had already experienced the new NKPA spirit at Yongdungpo, and on the 21st the 5th Marines contented itself with limited advances for the purpose of seizing high ground from which to launch the assault on Seoul. [315] O. P. Smith, _Notes_, 253–255. The attack on the 21st was launched astride the railroad by the 3d Battalion to the north and the 1st Battalion between the railroad and the river. After passing through the 2d Battalion, Taplett’s men seized three hills and by dusk were digging in on Hill 216, about six miles east of Hill 125 and the ferry landing site. The 1st Battalion had meanwhile advanced to Hill 96, about 3,000 yards southeast of yesterday’s Objective DOG, now occupied by the 2d Battalion in reserve. Further gains of some 2,500 yards to the southeast took the battalion to Hill 68, between the railroad and river, which was seized and held for the night. Enemy resistance ranged from light to moderate in both battalion zones. Between them, the 1st Battalion of the KMCs moved up to Hill 104, just north of the railroad and south of Sachon Creek.[316] [316] 1st MarDiv, _SAR_, Annex Queen Queen; O. P. Smith, _Notes_, 255–256.