In fact, the enemy did not launch another large-scale assault on Koto-ri after his costly repulse on the night of 28–29 November. Although the perimeter was surrounded throughout the first six days of December, incipient CCF attacks were broken up in the enemy’s assembly areas. Excellent observation as well as casualty evacuation was provided by the OYs taking off from the Koto-ri airstrip. They were the eyes of an impressive array of Marine fire power--tanks, 4.2-inch, and 81mm mortars as well as aircraft and Captain McClelland’s Easy Battery of 2/11. “The artillery 105’s and the mortars did a grand job,” commented Major Bartley. “They were always available, shifted their fires quickly and accurately, and serviced their pieces amazingly well in the cold weather.”[576] [576] Bartley ltr, 7 Feb 56. This section is also based on 1stMar _SAR_, 18–24, and the 2/1 _SAR_, 15–18. As a further asset, the Koto-ri perimeter was defended by adequate numbers in comparison to Hagaru during the first critical week of CCF attacks. On 30 November, when Baker Company of the 1st Tank Battalion returned to Koto-ri after the Task Force Drysdale battle, three platoons of tanks were added to the Dog Company platoon already attached to 2/1. The next day Colonel Puller’s RCT-1 (-) was further strengthened by the arrival of the 2d Battalion of the 31st Infantry, 7th Infantry Division, the last unit to reach Koto-ri from the south. These Army troops had been ordered to Hagaru, but owing to the changing situation they were directed by X Corps on 1 December to remain at Koto-ri. Under the operational control of Colonel Puller, 2/31 took over a sector at the southern end of the perimeter. Sporadic CCF small-arms fire was received on each of the first six days of December, and enemy troop movements were observed at all points of the compass. On several occasions a few mortar shells were lobbed into the perimeter. Not a single Marine casualty was suffered during the period,[577] though CCF losses were estimated at 646 killed and 322 wounded. [577] Not so fortunate was 2/31, which lost 5 KIA and 10 WIA expanding the perimeter to the south on 3 Dec. CO 1stMar msg to CG 1stMarDiv, 1850 3 Dec 50. Daily air drops were required to keep the perimeter supplied with ammunition, rations, and other essentials. Captain Norman Vining, the Battalion FAC, who had once been a carrier landing signal officer, guided planes to satisfactory drop zones with makeshift paddles. One day a case of .30 caliber cartridges broke free from its chute and hurtled through the top of Lieutenant Colonel Sutter’s tent during a conference. Narrowly missing several officers, it hit the straw at their feet and bounced high into the air before landing on a crate used as a table. _Assembly of Division at Koto-ri_