21 Feb After heavy mortar and artillery barrage, NVA company probes 37th ARVN Ranger lines but withdraws after distant fire fight. It is estimated that 25-30 NVA were killed. 23 Feb KSCB receives record number of incoming rounds for a single day--1,307. First appearance of enemy trench system around KSCB. 25 Feb B/1/26 patrol ambushed south of KSCB; 23 Marines KIA. 29 Feb-1 Estimated NVA regiment maneuvers to attack 37th ARVN Mar Ranger positions but fail to reach defensive wire. 6 Mar USAF C-123 shot down east of runway; 43 USMC, 4 USAF, and 1 USN personnel killed. 7 Mar Large groups of refugees begin to filter into the combat base and are evacuated. 8 Mar ARVN patrols attack enemy trenchline east of runway and kill 26 North Vietnamese. 15 Mar American intelligence notes withdrawal of major NVA units from Khe Sanh area. 23 Mar KSCB receives heaviest saturation of enemy rounds for the month of March--1,109. 24 Mar A/1/9 patrol kills 31 NVA west of 1/9 perimeter. 25 Mar 1/9 CavSqd, 1st ACD begins reconnaissance in force operations east of Khe Sanh in preparation for Operation PEGASUS. 30 Mar B/1/26 attacks enemy fortified position south of combat base and kills 115 North Vietnamese; 9 Marines are KIA. Operation SCOTLAND I terminates with 1,602 confirmed NVA and 205 Marines KIA; estimates place probable enemy dead between 10,000 and 15,000. Task Force KILO launches diversionary attack along Gio Linh coastal plain to divert attention away from Ca Lu where 1st ACD, and 1st Marines are staging for Operation PEGASUS. 1 Apr Operation PEGASUS begins; 2/1 and 2/3 (1st Marines) attack west from Ca Lu along Route 9. Elements of 3d Bde, 1st ACD conduct helo assaults into LZ Mike and Cates. Joint engineer task force begins repair of Route 9 from Ca Lu to Khe Sanh. 3 Apr 2d Bde, 1st ACD assaults LZs Tom and Wharton. 4 Apr 1/5 CavSqd moves northwest from LZ Wharton and attacks enemy units near old French fort; 1st Battalion, 9th Marines moves southeast from rock quarry and assaults Hill 471. 5 Apr 1/9 repulses enemy counterattack on Hill 471 and kills 122 North Vietnamese. 1st Bde, 1st ACD departs Ca Lu and assaults LZ Snapper. 6 Apr One company of 3d ARVN Airborne Task Force airlifted to KSCB for the initial link up with defenders.