Among these, decisive and highly confidential orders, which demonstrated the secretive and critical role of the cipher forces, served as keys unlocking the nation's historic victories.
Over the past 80 years of development and growth, generations of officers, soldiers, and personnel of the cipher sector have steadfastly overcome countless hardships, made silent sacrifices, and remained absolutely loyal to the Party and state. They have have excelled in their mission of maintaining the lifeline of communication, ensuring secrecy, safety, accuracy, and timeliness under all circumstances. The seemingly dry lines of code played a crucial role in securing resounding victories across battlefields, most notably the historic triumph of the Ho Chi Minh Campaign, which led to the complete liberation of the south and the reunification of the country.
Historic moments
According to Comrade Le Hong Huy, Head of the Department of Propaganda, Emulation and Commendation under the Political and Organisational Division of the Government Cipher Committee, right after the victory of the August Revolution in 1945, in order to promptly meet the urgent requirements for protecting state secrets and ensuring effective leadership, guidance, and command of the Party, government, and armed forces, the Party initiated the establishment of a communication system using coded messages from the central to local levels.
Following the directive of the Party Central Committee’s Standing Board, on September 12, 1945, the Military Cipher Division was officially established within the General Staff. This marked the predecessor of the Vietnamese cipher sector. Since that historic milestone, September 12 has been celebrated annually as the Traditional Day of the Vietnamese Cipher Sector — a special force known for its absolute loyalty, reliability, and commitment to ensuring confidentiality and the safety of information.
In the directive establishing the Military Cipher Division, President Ho Chí Minh clearly outlined its mission to ensure: seamless, confidential, swift, timely, and accurate command to defeat all enemies and protect the revolution. The great leader’s guiding thoughts on cipher operations laid a solid foundation for the formation and development of Vietnam’s cipher sector. These principles not only reflect the essence of cipher work during the resistance period but also define the motto and operational principles of Vietnam’s cipher sector over the past 80 years. They continue to serve as a compass for all generations of officers and soldiers in the cause of national defence and development.
After the signing of the Geneva Accords 1954, in response to the revolutionary tasks, on July 21, 1956, the Party Central Committee’s Secretariat issued Resolution No.10-NQ/TW on the establishment of the Central Cipher Committee. In August 1961, as the nation's resistance against American imperialism entered a particularly intense and arduous phase, the Central Office for South Vietnam established the Unified Cipher Committee to meet the need for secure leadership and command communication during the war.
During the historic Ho Chi Minh Campaign, the cipher force worked tirelessly day and night, demonstrating their intelligence and bravery to ensure the confidentiality, safety, accuracy, and timeliness of all leadership, direction, and command communications from the Party Central Committee, the Central Military Commission, the campaign’s command headquarters, and participating forces. Notably, the Telegraph Code Translation Office under the General Staff’s Department of the Cipher Directorate directly supported General Vo Nguyen Giap and the Supreme Command from March to April 1975, handling many historic secret telegrams.
Urgent Telegram No. 157 from General Vo Nguyen Giap, dated April 7, 1975, was sent to army corps, units, and military branches on their route to the battlefield; Telegram No.37, dated April 14, 1975, from First Secretary Le Duan; and Telegram from the Politburo, signed by First Secretary Le Duan, sent to the Command of the Campaign on April 22, 1975.
The most glorious moment came at 11:30 AM on April 30, 1975, when the liberation flag fluttered atop the Dinh Doc Lap (Independence Palace). At that time, comrades Mai Hoa Tham and Vong, members of the Cipher Unit of the Army Corps 2, urgently transmitted a telegram reporting the victory to the General Headquarters.
The history of warfare has proven that protecting information secrecy not only determines the success of individual battles, but also directly affects the outcome of entire wars. Comrade Le Hong Huy further noted that, starting with relatively simple cipher codes in the early days of its establishment, Vietnam’s cipher sector has continuously developed, building an increasingly diverse and sophisticated system of code regulations.
Those historic hours, when secret telegrams were being transmitted, carried not only information but also the very heartbeat of the nation — pulsing with the desire for reunification.
Silent contributions
According to comrade Nguyen Van Toan, Deputy Director of the Political-Organisational Department under the Government Cipher Committee, over the past 80 years, there has not been a single major campaign or battle that lacked the service of the silent army — the cipher force — who have consistently met the demands of leadership and command and even directly engaged in combat. Achieving those great victories would not have been possible without the sacrifices of hundreds of cipher martyrs, who heroically gave their lives for the independence and freedom of the nation, and for the mission of safeguarding the Party's confidential and critical information. Among them, many figures such as Hero of the People's Armed Forces, Warrant Officer Nguyen Van Giai, Head of Cipher Unit V4/49 of the Southern Intelligence Force, who died on December 26, 1968, and martyrs Doan Thi Chat and Le Hoang Ninh, have become enduring symbols of courage and sacrifice for the nation.
Fifty years after national reunification, the arduous and admirable work of the cipher soldiers have been fully learnt and appreciated. In the book "Unforgettable Memories", Sergeant Nguyen Van Khoi, a member of the Code Translation Unit under the General Staff’s Cipher Department, who worked at the "Dragon House" headquarters to serve Politburo and Commander-in-Chief Vo Nguyen Giap during the Ho Chi Minh Campaign, recounted: "We were accustomed to working around the clock, with a daily workload of 10 to 12 hours. The nature of our work demanded this, especially during campaigns. At such times, it was no longer just 10 to 12 hours a day, but 14 to 16 hours, sometimes even 24 hours for each person… Victory drove us forward. We were tired but incredibly exhilarated." Khoi passed away not long ago, following the death of Captain Vo Minh Chau, Deputy Head of the Telegraph Office; as of now, only Dang Thi Muon and Vu Thi Trong are still alive. It is known that the team was later reinforced by several others, but comrades Muon and Trong were among those who served from the very beginning to the final days of the campaign.
During a meeting with Muon in Hanoi ahead of the celebration of the Southern Liberation Day, she recalled how, in their office at the Thang Long Imperial Citadel, the Telegraph Code Translation Unit had translated and encrypted crucial and historical telegrams from comrades Le Duan, Truong Chinh, Pham Van Dong, Vo Nguyen Giap, Van Tien Dung, Le Trong Tan, Hoang Van Thai… sent to battlefield commanders and those reported back from the front. Their work involved not just encrypting and decrypting messages, but also conveying strategic orders and directives from the Party and State to the battlefields, maintaining seamless communications and safeguarding secrecy under all circumstances.
It was for this reason that the work of cipher soldiers like Muon, especially during the Ho Chi Minh Campaign, was so intense and urgent. She recalled that to meet the needs of the battlefield in late March 1975, nearly half of the Telegraph Cipher Division’s personnel were sent to the front. The remaining force at the unit was therefore very thin and consisted mainly of women, while the volume of telegrams from the battlefronts surged dramatically. There was a time when, during a shift handover, Muon reported as many as 473 telegrams overnight—a number that, — a number that, under normal conditions, would have taken them several days to translate and encrypt manually, relying solely on their eyes, hands, and utmost concentration, without any support from machines.
However, since the day she left her hometown of Tien Lu (Hung Yen) to enter the Military Cipher School in October 1967, then joined the Telegraph Cipher Division of the General Staff in June 1968, Muon has always been proud of her work. "We could work despite hunger and fatigue. Everyone’s eyes were dark-ringed and bloodshot after 12 to 16 hours each day, but it was not only driven by our yearning for independence and freedom but also by the responsibility and honour of a Party member and a cipher soldier," she said.
Having served in major campaigns such as Route 9–Southern Laos in 1971, the liberation of Quang Tri in 1972, and the Ho Chi Minh Campaign in 1975, now at the age of 77, the simple joys of the woman who spent 28 years with the Telegraph Cipher Division re gathering with her children and grandchildren and playing slight volleyball in the afternoons. Remarkably, although none of her three children join the Vietnam People’s Army and she suffers from occasional headaches and deteriorating eyesight, Muon affirms that if given the choice again, she would still choose the path of deciphering numbers and symbols in the cipher service, a demanding yet noble and honourable role.
At the historic moment on April 30, 1975, the nation's reunification, it can be affirmed that the cipher force had excellently fulfilled its historic mission, ensuring secure and uninterrupted communications, becoming an indispensable link in the nation's ultimate victory.
