Dyemarker was the code name for the planned barrier that was supposed to stop North Vietnamese infiltration. It was of special interest to Defense Secretary McNamara and the press dubbed it the McNamara Line. The original plan called for a barbed wire fence or barrier, like the Iron Curtain, with watch towers, bunkers, searchlights and electronic monitoring devices that would detect enemy movement and direct artillery on it. The barrier was to deny access to the eastern coastal plain and funnel North Vietnamese infiltration through the valleys that press hard against the western piedmont. The reality never came close to that. To say the Marines disagreed with this defense strategy was an understatement. They detested it. It went against everything the Marine Corps stood for: rapid deployment, and quick, offensive strikes. Most Marine officers felt defensive lines went out of style in World War I. A mobile defense of the DMZ was considered to be more effective. The McNamara Line was foisted on the Corps with the Marines complaining loudly. The Trace was an 11 kilometer long by 600 meter wide strip of cleared land that connected the firebases, known as Alpha Positions, just below the DMZ. Anything that was on that strip, be it forest, jungle or hamlet, was flattened by the bulldozers blade. The land was muted: hills shaved, valleys filled in. Construction of both the Trace and the firebases was done by the 11th Engineers. The Trace ran between the land's two major high points: Alpha 2 on the east, known as Gio Linh, to Alpha 4 on the west, known as Con Thien. Alpha 3 sat in the saddle between the two. Thirty-nine Dyemarker bunkers dotted Alpha 3 like sandbag islands. These structures were built to specifications of the Dyemarker plan, an eighteen by thirty two foot rectangular frame made of twelve by twelve inch timbers was set in a pit dug by a bulldozer. Rough cut, three inch thick planking was nailed to the frame. When that was completed the dirt was pushed back and half of the bunker was below ground level. Layers of sandbags were then laid on the roof and against the walls to a thickness of ten feet all around. They appeared much larger outside than in. Sheets of interlocking Marsden matting were interspersed between every two layers of sandbags to add strength and act as a bursting layer for delayed fuse shells. Leading down into the bunkers were two tunnels, each with a ninety-degree bend to prevent shrapnel from flying into the main room. The L shaped tunnels also kept out natural light and the flow of air. The bunkers were close, dark, and smelly. Although they were designed for eighteen men, up to twenty-six men crowded in each of these bunkers. Once completed they were safe from even a direct hit of North Vietnamese artillery. Encircling the outer perimeter of Alpha 3 was a nine-foot high barrier of concertina wire flanked on each side with double apron tangle foot. Inside that was a minefield two hundred meters wide that belted Alpha Three. It containing sixty thousand anti tank and anti personnel mines. Inside that was another razor wire barrier. Inside that was the MLR, the main line of resistance or simply the line -- a zigzag trench connecting all the fighting positions and fighting bunkers circling the base. At strategic spots along the line were M-48 tanks, twin 40mm Dusters, a tracked anti aircraft weapon, 106mm recoilless rifles, TPS-25 anti-personnel radar units and 50 caliber machine guns. It was a formidable defense designed to withstand a coordinated attack by infantry, tanks, and migs.
The war in Northern I Corps was conventional. There were no farmers taking pot shots with rusty French rifles. Each side had battalion size units stalking each other in free fire zones. Both were supported by artillery and tanks. And for each there was a trump card: the North Vietnamese could retreat to sanctuaries across the Ben Hai River, and for us there was air power. As a member of Tactical Air Control Party, TAC Party for short, I was a part of the directing end of that power. I loved my job. When the fast movers came on station if they didn't settle the dispute outright, they at least got everyone's attention. The function of TAC Party was to provide air support for the battalion. That included helicopter gunships strikes, medevacs, troop lifts, aerial observer spotter planes, and air strikes by jets. Enlisted men came from a specially trained section of Communications Platoon. The two officers in charge of us were aviators on temporary assignment from the First Marine Air Wing. One was the Air Liasion Officer (ALO) and he stayed in the Bn. command group. The other was the Forward Air Controller (FAC) who was tasked with actually calling in and controlling the close air support. But since we had four infantry companies and one FAC officer, the job often fell to the enlisted TAC Party operator.
Flight of CH-46's carrying troops to a combat insertion.
CH-46 lifting off LZ with medevac onboard.
O-1 Birddog Aerial Observer (AO)
A-4 Skyhawk loaded with snake & nape
F-4 Phanton flying feet wet
Napalm on Mutters Ridge
A4 Skyhawk pulling out after a drop.
Medevac for India WIAs after Feb. 16th fight inside the DMZ.