While Taylor and Phuong’s journey along the Ho Chi Minh Trail is fiction, the events leading up to it, including Taylor’s trip to South Vietnam as a civilian, and what they experienced along the way are all based on historical events and accounts. The notorious Hanoi Hilton that Taylor fears is his destination was unfortunately a real prison where captured Americans were tortured in North Vietnam. The Vietnam War was a deeply complicated conflict that divided the US in a way nothing had since the Civil War, starting in 1961, when President Kennedy sent Green Berets and military advisers to train South Vietnamese troops, and continuing until January 1973, when the last US troops left—a long and tragic twelve years later.

Vietnamese rebels had already been fighting French colonial rule since before World War II, finally defeating French forces in the famous Battle of Dien Bien Phu in 1954. The victory by Ho Chi Minh’s revolutionary army forced France out of Vietnam and led to the Geneva Accords, by which Vietnam was partitioned along the 17th parallel into communist-controlled North Vietnam, backed by China and the Soviet Union, and nominally democratic South Vietnam, supported—many would say controlled—by the United States.

The US began bombing North Vietnam and the Ho Chi Minh Trail in 1965 and sent the first US ground troops into South Vietnam that same year. The number of American troops in Vietnam grew quickly, from 185,000 in 1965 to a high of 535,000 three years later, fighting alongside nearly a million South Vietnamese troops in a war of attrition against the North Vietnamese Army and their Viet Cong guerrillas, who controlled hundreds of villages, towns, and even provinces throughout South Vietnam.

The Tet Offensive began on January 30, 1968, the start of the Vietnamese New Year, when 80,000 Viet Cong and North Vietnamese Army troops launched surprise attacks on more than one hundred South Vietnam towns and cities and military installations, including the capital, Saigon, where the attackers briefly overran the grounds of the US Embassy. The coordinated attacks came after the US government had assured the American public for months that the US and South Vietnam were winning the war, and that there was, in the words of then–Army Chief of Staff General William Westmoreland, “light at the end of the tunnel.”

Though initially successful, the Tet Offensive ended in military failure for the North Vietnamese Army, when all the captured cities and territory and installations were retaken in counterattacks by the US and South Vietnamese forces, who inflicted heavy casualties on the NVA. But the widely publicized attacks nonetheless shocked the American public, who had been led to believe that the enemy was too weak to mount any sort of massive and coordinated military campaign. With the rising number of American casualties, revelations of atrocities committed by some US soldiers, and mass protests against the war back home, support for the war fell in the aftermath of the Tet Offensive.

Support declined further when President Nixon ordered a resumption of the bombing in the North and in 1970 sent troops into Cambodia, widening the ground war at a time when an increasing number of Americans wanted it to end. Massive antiwar protests continued; the US began secret peace talks with the North; and in 1972, the NVA launched what was dubbed the Easter Offensive, once again attacking military bases throughout the South, and surprising the US and South Vietnamese forces. US troop levels, which also began a dramatic decline in the aftermath of the Tet Offensive, were down to 24,000 in 1972. The United States pulled the last of its troops from Vietnam a year later, in January 1973. The war ended in victory for the North Vietnamese two years after that when they defeated the South Vietnamese Army and entered Saigon on June 6, 1975.

The names of 58,307 Americans who died in the war are inscribed on the Vietnam Veterans Memorial in Washington, DC. Estimates of the total number of North and South Vietnamese, Laotians, and Cambodians killed in the war range from 1.5 million to 3.5 million, the majority of them civilians.

The US conducted nearly 600,000 bombing runs during the war and dropped more bombs on Vietnam, Cambodia, and Laos than had been dropped in all of World War II. Three million tons of those bombs—plus a near constant aerial spraying of chemical defoliants—were dropped on the 12,000 miles of roads, trails, and waterways that comprised what the North Vietnamese called the Truong Son Strategic Supply Route, and the Americans dubbed the Ho Chi Minh Trail. Hundreds of thousands of civilians and bo doi—NVA soldiers and trail workers—were killed or wounded in the bombings and spraying and clandestine assaults by US and South Vietnamese units. But the supply route, also called the Reunification Trail, or sometimes Blood Road, was never broken.

An estimated 80 million of 270 million cluster bombs dropped in Laos during the war—the baseball-size “bomblets” like the ones described in this story—remain in that impoverished country today, where hundreds of civilians still die every year from delayed explosions.

In the novel, Taylor Sorenson quotes his father as saying, “We had to destroy the village in order to save it.” That quote, in slightly altered form, is borrowed from a February 7, 1968, dispatch by journalist Peter Arnett, writing about a small provincial capital in South Vietnam, and a US Army major’s explanation for the decision to bomb the town to force out the Viet Cong, regardless of civilian casualties: “It became necessary to destroy the town to save it.”

I am indebted to Virginia Morris and Clive Hills, who traveled the length of the Trail a decade ago, for their important contemporary study A History of the Ho Chi Minh Trail: The Road to Freedom, and to John Prados for his exhaustive political and historical account, The Blood Road: The Ho Chi Minh Trail and the Vietnam War. For insight into the lives of those who came down from North Vietnam to bring the fight to the South, I am deeply appreciative of Dang Thuy Tram’s recently discovered wartime diary, published posthumously thirty years after she was killed in the war, Last Night I Dreamed of Peace. The New York Times Vietnam ’67 series was enormously helpful, especially Ron Milam’s essay “1967: The Era of Big Battles in Vietnam,” and Hai Nguyen’s “As the Earth Shook, They Stood Firm,” both important accounts of the decimation of the village of Ben Suc. While I have relied on these and other sources to help ensure historical accuracy in On Blood Road, any mistakes are, of course, my own.