Le Duan, the head of the Vietnamese Communist Party since 1969, quietly fostered far-reaching policies that shaped the takeover of South Vietnam and tied Hanoi to the Soviet Union.
A fervent supporter of decisive action, Duan in the 1950s persuaded Hanoi to apply military pressure in rival South Vietnam, laying the seeds of terrorism that sparked the U.S. military involvement in the embattled nation.
After the war, he led Vietnam's break with China and brought his nation much closer to the Soviet Union. The country became dependent on Soviet military and economic aid.
References to Duan's birthdate conflicted but April 7, 1907, was the most recognized.
The son of a railroad clerk, he was born in former Quang Tri province, now part of central Vietnam's Tri Thien province, straddling the old 17th parallel Demilitarized Zone.
He was still a teenager when he helped found the Indochinese Communist Party, which later was banned.
Like many of Vietnam's aged leaders, he was jailed in the French political prison on Con Son Island, then known as Poulo Condore. There he and Pham Van Dong, who became the Vietnamese premier, turned the prison into a school for communist studies.
In 1945, the communist Vietminh freed Duan from nearly 10 years imprisonment.
A year later, Duan became the Communist Party's chief political commissar in South Vietnam. He quickly gained his reputation by working in the jungles south of Saigon (now Ho Chi Minh City) until 1959.
Some who knew Duan called him a tyrant, while others described him as a pragmatic, compassionate leader. He eventually became known as Ho Chi Minh's 'Southern Connection.'
The low-profile Duan never held high government office. His life was the Communist Party and he believed it held all the solutions.
After the Vietnamese communists defeated the French in northern Vietnam in 1954, Duan remained in the south, directing subversive activities as secretary of the Communist Party of South Vietnam.
In 1956, he was promoted to the daily administration of North Vietnam's Communist Party. It was at the expense of Party Secretary General Truong Chinh, who had directed a disastrous land reform movement but would later re-emerge to become president and bear unpleasant memories of Duan.
Duan became impatient with the 'political struggle' in South Vietnam and urged Hanoi to employ more military tactics.
After a secret trip to the south in 1959, Duan finally persuaded Hanoi to break the 1954 Geneva Agreement that partitioned Vietnam and prohibited military buildups by either Vietnamese regime in each other's territory.
Units quickly were sent south through the Ho Chi Minh Trail and the fighting began in earnest.
The same year, Duan formally was appointed Party Secretary General or First Secretary. Only Party Chairman Ho Chi Minh was more powerful politically.
In 1960, he called on Vietnamese nationalists in the south to form an anti-American political front. That propelled the creation of the National Liberation Front, the southern political arm of the communists.
When Ho died in 1969, Duan became the head of the Communist Party but declined to be named chairman. He preferred to stay mostly in South Vietnam rather than Hanoi.
In early 1978, Duan resisted an inter-party struggle to overthrow him. He later solidified his power base by appointing allies and relatives to important party posts.
During his later years, Duan's health declined and he appeared in public infrequently.