When asked in the early 1960s to identify the most daring and consequential attack the enemy could plausibly mount, General William Westmoreland, the commander of U.S forces in Vietnam, bluntly offered: “Capture Hue.” Years later, on January 31, 1968, first day of the Vietnamese New Year, the combined forces of the North Vietnamese Army and the Viet Cong launched a stunning country-wide assault in an attempt to permanently shift the war’s course. And sure enough, the Tet Offensive’s cornerstone was seizing and holding Hue, a fortified, strategically important South Vietnamese city.

Mark Bowden’s Hue 1968: A Turning Point in the American War in Vietnam is the definitive history of the battle for Hue. It is the result of years of archival research and dozens of interviews in the U.S. and Vietnam and told largely through participants’ first-person recollections.

Hue was a signal event in Southeast Asian and U.S. history. Bowden, the mega-best-selling author of Black Hawk Down and Killing Pablo, labels the battle

the bloodiest of the Vietnam War, and a turning point not just in that conflict but in American history. When it was over, debate concerning the war in the United States was never again about winning, only about how to leave. And never again would Americans fully trust their leaders.

Hue, the third-largest city in South Vietnam with a population of 140,000, was an important city for both the North and the South Vietnamese. It was a the former imperial seat, the center of Vietnamese culture, and a major center of learning and worship. Bowden reconstructs the Battle of Hue in vivid, painstaking detail. It is a riveting account, certain to become a motion picture, of valor, heroism, rank foolhardiness, and unshakable camaraderie. Soldiers, Marines, sailors, and journalists on both sides receive thorough, sensitive treatment in life and death.

After weeks of careful, clandestine preparation, at dawn on January 31, 1968, the North Vietnamese Army and the Viet Cong completed their blitzkrieg in a matter of hours, taking command of Hue’s hitherto forbidding Citadel and swiftly hunkering down in indomitable defensive positions. They held the city for nearly a month, inflicting nearly 5,000 casualties on U.S. and South Vietnamese forces, who fought to retake it in brutal block-by-block street-fighting.

The retelling, like the battle itself, begins slowly, with American forces convinced they’d swiftly quell what the brass insisted was a small rebellion, but promptly gives way to vicious fighting over key landmarks both inside and outside the Citadel, and critical ancillary battles over supply lines. Bowden recounts the experiences of doughty but shell-shocked Marines, formidable but outgunned Viet Cong, and terrified civilians alike.

Along the way, Bowden rehearses all the familiar critiques of American political and military decision-making (the creation of and reliance on bogus statistics; the inflation of casualty figures and kill ratios; the faulty belief that enemy morale was always on the precipice of collapse) and occasionally succumbs to overly romanticizing the VC (“The Front troops had nothing like the firepower of American and ARVN troops, and they lacked the ability to attack and resupply by air or sea, but they had deep roots in the community”).

That said, he remains clear-eyed and unsentimental about the ruthless and doctrinaire North Vietnamese regime, which he characterizes as “modeled on the Soviet state and deeply influenced by Mao’s ongoing Cultural Revolution…It promised a state-run economy and society ruled by the party where allegiance to the regime was absolute.”

Groupthink afflicted party leaders, who expected the oppressed people of South Vietnam to rise up in support of the VC, if given the chance. The leadership in Hanoi were “virtuoso songbirds of propaganda. They lived in a bubble. There were no voices of dissent in their society to check or challenge wishful thinking. And they were certain of their ultimate victory.”

Bowden also explains how an aging Ho Chi Minh himself was unsettled by the NVA and VC’s brutality and fretted that their vicious and often vindictive approach would spark a popular backlash. “The party and the army were not enough,” Ho and his devotees believed. “Real victory could come only from the people.”

But when push came to shove, the trapped civilian population of Hue proved compliant, if unenthusiastic, about its communist occupiers, whose strenuous indoctrination and enlistment efforts, mass executions, and forced reeducation programs hardly endeared them. “After the first days of the occupation,” Bowden writes, “it was apparent that the party’s goal of a ‘general uprising’ was stillborn.”

Liberation of the city, however, proved equally complex. Some 8,000 civilians perished during the weeks-long purges and battle—which for the U.S. included the harshest, grisliest urban fighting since the 1950-51 struggle for Seoul—and an estimated 80% of the city’s buildings were damaged or destroyed. If the campaign to retake Hue didn’t exactly destroy the city to save it, it came pretty close.

Hue’s aftermath proved no more forgiving to allied forces, especially the military brass and their political masters. Barely a month after the city’s liberation, a chastened President Johnson, who’d received and conveyed countless overly optimistic accounts of the war, announced he wouldn’t seek reelection. Two months afterward, the ineffective and body-count-obsessed Westmoreland—fearful of a phantom offensive at Khe Sanh that never arrived; unprepared for and dismissive of the assault on Hue that did—was relieved. Bowden even credits Hue with provoking Walter Cronkite’s famous, and consequential, turn toward skepticism of the war effort.

But more than anything, Hue 1968 is the story of the entire Vietnam War in microcosm. Ideologically-driven Viet Cong and North Vietnamese forces—call them communists, nationalists, or both—proved both repressive and unexpectedly resilient, able to overpower the South Vietnamese and surprise the Americans. And while allied firepower ultimately dislodged the invaders, victory’s costs were immense and deeply dispiriting.

It’s possible, of course, that had the U.S. and ARVN continued fighting relentlessly, they could eventually have exhausted the enemy; something similar happened in the early 1970s and resulted in the Paris accord. But the North regarded that agreement less as a treaty than a brief pause, enabling rearmament and renewed attack, and it was the South and the U.S. who themselves were too exhausted to resist effectively. In the end, Hue, indeed, appeared to foretell the war’s end-result.