It was not the isolation that was hardest to endure, though it lasted nearly three decades. Nor was it the cold of his cell, where he was often chained naked, nor summer's blistering heat, nor the rusty shackles that infected his legs, nor the relentless hunger.
It was, Nguyen Chi Thien said afterward, the utter lack of access to the written word: no books, no newspapers and, more devastating still for a poet, not so much as a pencil or a scrap of paper.
He kept writing anyway, producing songs of love, howls of protest and hundreds of other poems -- some 700 in all -- each one composed, edited, revised and stored entirely in his head for a posterity he was not sure would come.
Mr. Thien, a dissident writer who has been called the Solzhenitsyn of Vietnam for the sheaves of poems he wrote opposing the communist government there -- and for the prolonged imprisonment, including torture and solitary confinement, that his efforts earned him -- died Oct. 3 in Santa Ana, Calif. He was 73.
The apparent cause was respiratory illness, said Jean Libby, a friend who has edited English translations of his work. Mr. Thien, who was allowed to leave the country in 1995 and became a U.S. citizen in 2004, had been ill with emphysema for many years and had suffered from tuberculosis nearly all his life.
His health had been broken by his 27 years in Vietnamese prisons and labor camps, including half a dozen years in the "Hanoi Hilton" -- the name, born of bitter irony, bestowed by captured U.S. servicemen on the Hoa Lo Prison there.
Mr. Thien's odyssey began on an otherwise ordinary day in 1960, after he had attempted to correct a piece of the communists' revisionist history before a class of high school students. By the 1980s and '90s, his case had become an international cause celebre, taken up by the human-rights group Amnesty International and the writers' organization PEN International, among others.
Mr. Thien was considered one of the foremost poets of contemporary Vietnam, often mentioned in world literary circles as a candidate for the Nobel Prize in Literature. Of the 700 poems he wrote in prison, "70 to 100 would be considered masterpieces in our language," Nguyen Ngoc Bich, one of his translators, said.
Mr. Thien's best-known work, the book-length verse cycle "Flowers From Hell" -- which he managed to slip into Western hands, at great personal cost, during one of his rare moments of freedom -- was published in the U.S. in English in 1984 and has been translated into many other languages.
For all his renown, Mr. Thien spent his last years quietly in the Vietnamese diaspora in Orange County, Calif., known as Little Saigon. He occupied a series of rented rooms and, most recently, a federally subsidized apartment in Santa Ana, reading, writing, lecturing and making political broadcasts on Vietnamese-language radio and television stations throughout the United States. He lived modestly, sustained partly by public assistance and donations from supporters but unable to afford medical insurance.
The youngest child of a middle-class family, Nguyen Chi Thien was born in Hanoi on Feb. 27, 1939. He resolved early on to become a writer, a decision that in the Vietnam of the period was virtually synonymous with becoming a poet.
The course of his life was determined in 1954, after his native country was partitioned into North and South Vietnam. His parents, believing the communist leaders of the north would be good for the country, chose to keep the family in Hanoi.
Young Mr. Thien's political troubles began in 1960, after he agreed to fill in for an ailing friend who taught high school history. He noticed that the students' textbook falsely claimed that the Soviets had brought about the Japanese surrender in World War II.
Mr. Thien told the class that in fact, Japan had surrendered after the U.S. dropped atomic bombs on Hiroshima and Nagasaki. He was arrested soon afterward.
He was sentenced, without trial, to 31/2 years' hard labor. It was then that he began composing poems in his head.
Released in 1964, Mr. Thien worked as a bricklayer, reciting his poems covertly to close friends. In 1966, he was arrested again on suspicion of having written those poems, which by then were circulating orally in Hanoi and elsewhere. He spent nearly a dozen years in North Vietnamese re-education camps, again without trial.
In 1977, two years after Saigon fell to the communists, Mr. Thien was released along with many other political prisoners: Hanoi wanted to make room in its jails for the thousands of South Vietnamese officials it was then imprisoning.
He knew that his chances of rearrest were great, and he was not certain, he later said, that he would survive a third incarceration. He feared his work would die with him.
In secret, he set down on paper as many poems as he could recall -- about 400 -- which took three days of continuous writing. He took the manuscript to the British Embassy in Hanoi, where he managed to evade the guards long enough to slip inside.
He asked the British officials there for asylum, which they said they could not grant. He asked them to see that his poems reached the West, and that, they said, they would do.
On leaving the embassy, Mr. Thien was arrested and imprisoned without trial for the third time. He spent six years in Hoa Lo, three of them in solitary confinement, followed by another six years in prison camps.
Unbeknownst to him, his manuscript was making its way around the world during this time, passed from hand to hand in Britain and the U.S. In 1984, the Council on Southeast Asia Studies at Yale University published it as "Flowers From Hell," translated by Huynh Sanh Thong.
The next year, the volume won the Rotterdam International Poetry Award, presented to Mr. Thien in absentia.
The award brought his case to the attention of human-rights groups, which helped locate him and lobbied on his behalf. He was released from prison in 1991, weighing 80 pounds. After spending the next four years under house arrest in Hanoi, he was allowed to leave for the U.S.
Mr. Thien never married.