"CUT their supply lines and bleed the Americans to death on the DMZ," the Communist order read.

And with a strategy tantamount to killing an unborn baby by severing its umbilical cord, the Viet Cong struck at the Navy Seabees.

The attack came out of the jungle bordering a 16½-mile stretch of shell-pocked Route 1 between Phu Loc and Lang Co in Vietnam's coastal lowlands.

Mortar rounds rained out of the sky like exploding hail, ripping at bulldozers and rock crushers, caving in culverts, blasting newly-built bridges and sending lethal shrapnel in a deadly search for scurrying construction crews.

When the attack was over, beaten back by the Marine units providing security for the Navy force, the Seabees remounted their battle-scarred dozers and began the task of reopening the lifeline to the DMZ.

"Blood, sweat and pure guts is keeping the vital road link open between Hue and Da Nang," said an American officer.

"If the VC blow this new bridge, we'll build another right alongside," declared Seabee Petty Officer Daniel J. Gomez, operating a pile driver outside Phu Loc.

Gomez and 61 fellow Seabees are members of Tango Detail of the Naval Mobile Construction Bn. 74. Seventeen of their crew have been bled by VC gunshot since they took over the task of keeping the 16½ miles of road open between Phu Loc and Lang Co last August.

Two days after they completed one important bridge link in the road, the VC blew it up. And the dawn of many a day has found huge trenches making the road impassable at spots the Seabees have labored long and hard to make freeway-smooth.

The road has become a war within a war, pitting the destructive skill and determination of the VC guerrillas against the constructive might and determination of the U.S. Seabees.

"It's becoming a simple matter of showing the VC who's boss over this stretch of highway," said Lt. George P. Hibbard, officer-in-charge of Tango Detail. "And there isn't. any doubt in our minds that the convoys will keep rolling toward the DMZ."

Watching the Seabees remount their battered machines and begin rebuilding their road after a Cong attack is reminiscent of an old John Wayne movie about the famed Navy crews in World War II.

And Seabees like Gomez of Baton Rouge, La., shrug off the hazardous duty of their present assignment as if it. were an expected part of the routine.

"It, can be discouraging to see the fruits of your labor go up in smoke from a VC attack," said Senior Chief Builder Dewey D. Ray, "but it isn't hard to rebuild your morale and the bridges in light of what the guys are going through at the DMZ end of the line."

Currently, the hard-pressed 62-man detail is engaged in construction of two bridges, installing 28 culverts, filling potholes and shell holes along the entire length of the road and completely resurfacing 2½ miles of road north of Lang Co.

The Seabees, assigned to the 3rd Naval Construction Brigade, are also upgrading roads and building bridges from below Quang Ngai City along Route 1 to the DMZ, along "Rocket" Route 9 from Khe Sanh to Dong Ha, and across the Hue Bypass.

Pfc. Roger Spradley, a member of Echo Co. 2nd Bn., 26th Marines, guarding the Seabecs of Tango Detail, has no doubt. as to who is boss of Route 1.

"These guys never lose heart," the 19-year-old Leatherneck declared. "No matter how much they get shot at, they go back and get the job done again in short order."