Week of July 2
Operation Thor, the joint mission to attack and destroy North Vietnamese long-range artillery facing the Demilitarized Zone (DMZ), coast artillery batteries, antiaircraft positions, and staging areas for infiltration, supplies and transport, took place July 1 - 7, 1968. The targets were in the Cap Mui Lay sector, the furthest southern coastal area of North Vietnam. It ran up the coast from the southern edge of the DMZ for almost nine miles, and inland just more than 15 miles.
Preparation for Operation THOR called for the movement of artillery batteries to prepared temporary positions. U.S. Marine and Army artillery in THOR included three Army Battalions of 175mm guns and 8 inch howitzers, and six Marine batteries of 155mm and 8 inch guns and howitzers. Naval gunfire support came from two cruisers and six destroyers. United States Air Force aircraft included the entire 3rd Air Division of B-52Hs based on Guam, five Tactical Fighter Wings, two Tactical Reconnaissance Wings, and light spotter aircraft from the 20th Tactical Air Support Squadron. The First Marine Air Wing employed consisted of five Attack Fighter Squadrons, five Attack Squadrons, and a Reconnaissance Squadron. Lastly the U. S. Navy provided 13 fighter and attack squadrons flying from four aircraft carriers. Extensive target lists were compiled ahead of the operation.
In the first phase of Operation THOR 664 U.S. aircraft and 114 B-52 sorties attacked in concert with the Navy cruisers and destroyers. These attacks, lasting two days, destroyed and damaged enemy installations. Damage to antiaircraft and coastal batteries enabled spotter aircraft and naval vessels to approach targets closer than previously possible. By the beginning of Phase Two, the third day of Operation THOR, improved reconnaissance had enlarged the target list. Artillery of the land forces and the Navy's cruisers and destroyers continued to fire against North Vietnamese antiaircraft positions. By the beginning of Phase Three, light Marine and Army Spotter aircraft were able to operate well into North Vietnamese airspace. Their presence allowed engagement of more targets with greater accuracy. Observers reported that little or no farming or other domestic activity was occurring in the Cap Mui Lay sector. Observers on the ground in the air and at sea recorded the impact of the strikes. Over 600 secondary fires and explosions were observed. The operation ended the night of July 7.
By the end of the mission, 8,363 tons of bombs were dropped and 42,209 shells were fired. One Army soldier and one Air Force pilot were killed. Six aircraft were lost. An estimated 789 antiaircraft and 179 artillery pieces or positions were destroyed along with other installations and material. The long-term impact of this short campaign was that American observation aircraft were able to fly over the region, and antiaircraft fire was reduced by 80% until overflights of the North were banned by President Johnson on November 1, 1968.1
1Jack Shulimson, Marines in Vietnam the Defining Year 1968 (Washington DC, History and Museum Division USMC: 1997) pp. 359-361; Raymond Blum, The Vietnam War A Chronology of War (New York, Universe: 2010) p. 184; Walter Hixon, Military Aspects of the Vietnam Conflict Volume 2 (New York, Garland:2000) pp. 220-8