LYNN – Nobody wanted to go down the jungle trail. They just had a bad feeling about it. Besides, the foliage seemed too matted down, as if a phalanx of troops had gone before them, and in these parts, that could only mean the enemy. But the ranking officer insisted, so off they went, mostly young American soldiers walking directly into the jaws of a North Vietnamese Army ambush.When the shooting stopped and the smoke cleared, soldiers lay dead, including Marine Lance Cpl. Kevin A. Cahill of Lynn. He was 19. It was Thursday, Oct. 12, 1967, deep in the Hai Lang Forest of South Vietnam.An account of that tragic day is prominently mentioned in a new book, “Lions of Medina” by historian Doyle D. Glass, who chronicled the valor of U.S. Marines during the Vietnam War.The title refers to Operation Medina, a harrowing sweep and blocking operation in the dense forest that began two days before Cahill was killed. The story follows the Marines and Navy corpsmen of Charlie Company, First Battalion, First Marines, First Marine Division.To glean the details of what transpired during those days in country, Glass interviewed over 75 veterans, and the family and friends of those who didn’t return.Cahill was assigned as point man at the head of the column the day they entered the wide, trampled trail. Fellow Marines said he possessed a keen sense of danger. He had done this before, but this time voiced his displeasure at the orders, preferring the relative safety of the bush.Glass wrote: “All was quiet as the men moved forward. Suddenly, the stillness was shattered by the deafening staccato crack of a machine gun. Small arms fire tore through the column of men. Grenades fell from the sky like rain, sending shards of hot shrapnel through the Marines as they detonated.”The predictable, yet lethal, ambush had been sprung. The North Vietnamese had been waiting for the Marines on the well-concealed hill. Cahill dropped with the first blast of machine gun fire.”More grenades were tossed. Other Marines, like Cahill’s good friend Doff Edwards, were badly wounded. First Lt. Paul Nelson picked up Cahill and carried him until another blast knocked them to the ground. A medic began working on Cahill, putting a battle dressing on his most serious wounds, but the Marine was bleeding internally. Cahill lost consciousness and died on the battlefield. Minutes later, the ambush was over.Glass: “Cahill’s sudden death stunned many of the Marines who knew him. He was a likeable Marine with a great sense of humor and a strong Boston accent that often made others laugh.”Others on Cahill’s fire team called him KC. Private Edward Krisko, a rifleman, described Cahill as a Marine’s Marine, noting how he was always at the front and would check out a situation himself before sending his comrades.That day in the jungle, an evacuation helicopter eventually arrived, its rotor wash creating a manmade hurricane. Cahill’s body, wrapped in a poncho, was loaded aboard.Nelson, the lieutenant who ordered Cahill onto the trail and who later tried to save him, still blames himself. “If I hadn’t made the effort to save him, it would have been very difficult to live with myself from that day forward,” Nelson told the author.Many of the surviving Marines remain haunted by Operation Medina.A fading photograph published in The Item on Nov. 25, 1967, shows the dead soldier’s parents, Thomas and Veronica Cahill, formerly of 211 Lynnfield St., accepting a Purple Heart and other military commendations from an Army captain. A city square, near the intersection of Lynnfield Street and Mazza Road, was later named in Cahill’s honor.Cahill’s mother has since passed away, but his father, a WWII veteran, still lives in Lynn. The Marine’s brother, Thomas, is married to the former Mary Jane Rooney and lives on Lynn Shore Drive. The couple has three sons n Daniel, currently a member of the Lynn School Committee, William, and Kevin. The latter was named for his Marine uncle, and is a U.S. Army major servi