Evacuation of the wounded was the chief problem on 2 December, when it became evident that previous estimates of losses at Yudam-ni and among the Army troops east of the Reservoir were far too low. A total of 914 casualties were flown out by the C-47s and R4Ds that day and more than 700 on the 3d. Captain Hering and his assistants had assumed that the Air Force evacuation officer was screening the casualties until he informed them that this was not his responsibility. The Division surgeon then set a Spartan standard. He passed personally on all controversial cases and approved for evacuation only those in as bad shape as Lieutenant Commander Lessenden, the 5th Marines surgeon who had refused to be flown out and continued on duty after both feet were painfully frozen. Apparently it was not too severe a test for men who could stand the pain, since Lessenden suffered no permanent injuries.[537] [537] Bureau of Medicine and Surgery, U. S. Navy, Public Information Release, 21 Apr 51; LCdr J. H. Craven, (ChC) USN, interv by HistDiv, HQMC, 22 Oct 52; Hering, “Address Before U. S. Association of Military Surgeons, 9 Oct 52.” Captain Hering had to use his medical authority in several instances to overcome the objections of Yudam-ni casualties who declined evacuation, though in obvious need of hospitalization.[538] [538] _Ibid._ Study of the frostbite casualties of the Chosin Reservoir campaign led to the adoption of the thermal boot as an effective preventive measure during the operations of the following two winters of the Korean conflict. The liaison airstrip at Koto-ri had been of little use, since it was outside the perimeter and exposed to enemy fire. But the completion of a new strip on the 2d made it possible to evacuate about 47 casualties that day from the 2/1 perimeter.[539] [539] 2/1 _SAR_, 16; LtCol W. S. Bartley ltr, 7 Feb 56; X Corps, _Special Report, Chosin Reservoir_, 93; Smith, _Notes_, 844; VMO-6 _SAR_, 13–18. More than 1400 casualties remained at Hagaru on the morning of 5 December. They were all flown out before nightfall, making a total of 4312 men (3150 Marines, 1137 Army personnel and 25 Royal Marines) evacuated from Hagaru by air in the first five days of December, according to Marine figures.[540] X Corps estimated a total of 4207 for the same period.[541] [540] Smith, _Notes_, 998–999. [541] X Corps _Special Report, Chosin Reservoir_, 93.