Chinese Support for North Vietnam during the Vietnam War: The Decisive Edge
by Bob Seals
“Best turn it into a bigger war…I’m afraid you really ought to send more troops to the South…Don’t be afraid of U.S. intervention, at most it’s no worse than having another Korean War. The Chinese army is prepared, and if America takes the risk of attacking North Vietnam, the Chinese army will march in at once. Our troops want a war now.” 
-- Mao speaking to the North Vietnamese in 1964
So why did the powerful modern nations of France and the United States lose two wars in Vietnam to a third rate military power like North Vietnam? This is the logical question that many historians have asked and attempted to answer since the Second Vietnam War ended in April 1975 with the fall of Saigon to North Vietnamese tanks. Some historians have stressed the support of the Communist party and its leadership, others point to the support of the Vietnamese people, and still other historians explain the North Vietnamese victory as an effect of the post-colonial nationalism wave that swept through Asia after the Second World War. However, few historians, with the possible exception of Qiang Zhai, among others, attribute the victory of the Vietnamese Communists in both Vietnam Wars to the considerable support provided by the communist colossus of the north, the People’s Republic of China.  This Chinese military support, to include equipment, advisors and planning assistance, provided from 1949-1975, would prove in both the First and Second Indochina Wars to be decisive. This substantial military support would give the People‘s Army of Vietnam an edge to resist Western forces and eventually subjugate the Republic of South Vietnam. This support, for various reasons, has never really been acknowledged by most popular histories of the conflict. This is perhaps due to the fact that such acknowledgement of the massive Chinese military support provided challenges many cherished myths of Vietnamese Communist military brilliance and the “heroic struggle” against overwhelming western imperialists. Two recent histories bear this out. Case in point A Military History of China, edited by David A. Graff makes no mention of Chinese support for Vietnam while Bruce A. Elleman’s Modern Chinese Warfare, 1795-1989, dismisses Chinese support in a mere two sentences.  However, unless this decisive Chinese support is properly understood by students of both Vietnam wars the answer to the question of why North Vietnam won will remain incomplete and misunderstood. This paper will attempt to outline the Chinese communist support in both wars and explain exactly why this support was so decisive.
As with most historical events one must first understand, in broad general terms, the background and context to a specific point in time. A brief review of the historical Sino-Vietnamese relationship sets the tone for more recent events, in many respects. Ties between China and Vietnam have existed for centuries; in fact, throughout history Vietnam has depended upon and looked towards China repeatedly for not only cultural but political assistance as circumstances warranted. Vietnam was considered by China to be part of her tributary system, or sphere of influence if you will, where by the lesser state, Vietnam, would acknowledge the leadership of Imperial China in return for trade and defense as required. In the 18th century, for example Chinese troops intervened in Vietnam to assist a threatened ruler and again less successfully in the latter half of the 19th century against France expanding her influence in the area, with the so-called “Black Flag” forces. This concern for Vietnam would continue with China declaring war on France on 27 August 1884, in fact, due to French expansion into Northern Vietnam. 
This traditional relationship between China and Vietnam was not always harmonious as many have pointed out, since, for obvious reasons, no nation enjoys domination by a more powerful neighbor.
The Chinese Vietnamese Communist ties had existed for decades, in fact, before the first Chinese military advisor arrived in North Vietnam in 1950. The life of Nguyen That Thanh, who would ultimately be known to the world under the pseudonym Ho Chi Minh, best personifies the close relationship that existed between the two communist parties, and ultimately the two armies.
The ties go back to right after the First World War, in fact. In 1920 Ho would be one of 285 delegates, and the only “Comrade Indochinese Delegate,” that founded the French Communist Party in Tours.  Ho made an impassioned speech at the conference listing France’s crimes in Vietnam “…we have not only been oppressed and exploited shamelessly, but also tortured and poisoned…we have been poisoned with opium, alcohol, etc.” 
The following year the Chinese Communist Party would be formed in 1921. The party from the beginning would serve as a rallying point for disgruntled Vietnamese such as Ho, and others, wanting to resist French rule in Vietnam.  After several years of training in Moscow, Ho eventually made his way to China, the then front lines of the revolution, to assist Mikhail Borodin, the Communist International, or COMINTERN representative to the new Nationalist government of Sun Yat-sen. Organizing Vietnamese revolutionaries in Canton, Ho lectured at the famous Nationalist Whampoa Military Academy, meeting such communist luminaries such as Zhou Enlai and others, before returning to Moscow after the Chinese Nationalist-Communist split in 1927.  He would also organize the Indochinese Communist Party in 1930 which in time would become the Vietnamese Worker Party. A dedicated COMINTERN agent who traveled on a Soviet passport, Ho was known as Nguyen Ai Quoc (Nguyen the Patriot) during this period and would only be known as Ho Chi Minh (Ho the Enlightened ) after 1943. He would travel between Asia and Moscow before finally returning to China in 1938 to serve as an advisor to the Chinese Communist 8th Route Army, along with other senior Vietnamese revolutionaries.  Ho became quite proficient in Chinese and would translate Mao’s celebrated work, “On the Protracted War,” from Chinese into French. 
Second World War and French Reoccupation
Seasoned by years of training and his experiences China Ho would found the Viet Minh independence movement in 1941, the Vietnamese Doc Lap Dong Minh Hoi, the League for the Independence of Vietnam, or Viet Minh. He would spend the remainder of the war organizing in the north of Vietnam and attempting to remain out of French and Chinese jail. During the war the Viet Minh would consolidate their power in the north of Vietnam with history teacher turned General Vo Nguygen Giap building communist forces reaching some 5,000 in number. 
By the time the Second World War ended in August of 1945, with the collapse of Imperial Japan, the organized and disciplined Vietnamese communists and Ho were perfectly positioned to move into the power vacuum left in the wars wake in Vietnam. In September of 1945 Ho would proclaim the establishment of the Democratic Republic of Vietnam (DRV) with American Office of Strategic Service (OSS) officers beside him in Hanoi. Nationalist Chinese and British troops that same month arrived to take the surrender of the Japanese forces, with reoccupation by the returning French soon afterwards. A period of unease settled over Vietnam with the French and Vietnamese negotiated over the future of Vietnam, with Ho at one point traveling to Paris for unsuccessful meetings with the French government. Ho would formally request military aid to include advisors and equipment from Stalin and the USSR in 1945, with no response to these requests given in return.  The Chinese in the future would not make the same mistake.
First Indochina War
The First Vietnam War would finally begin in December of 1946 as the French attempted to disarm the Viet Minh Self Defense Forces in Hanoi and full scale fighting broke out.  By early 1947 the French had driven the Viet Minh out of the major cities throughout the country but the communists controlled the countryside in the north with a growing army of some 50,000 men capable of standing up to the best the professional French Army and Navy could throw at them.  The war settled down to a deadly affair of guerrilla war, ambush and counter ambush as the Vietnamese and French forces fought for control of Vietnam and the population.
It was during these early years of the war that the Chinese military support of the People’s Army of Vietnam (PAVN) began on a rather minor scale. This military aid started in March of 1946 as the Chinese Communist First Regiment of the Southern Guangdong People’s Force crossed into Vietnam in order to avoid Chiang Kai-Shek’s Nationalist 46th and 64th Armies during the Chinese Civil War.  In addition to avoiding destruction this Chinese Regiment would begin to lay the groundwork for training and advising the less mature Vietnamese forces. This one thousand man unit of the Chinese People’s Liberation Army, PLA, would provide officers to the Vietnamese Advanced Infantry School and Cadre Training Center in North Vietnam with some 830 personnel trained by the year 1947.  Direct contact to include cable traffic and funding existed at this early point between the two communist movements.
The strategic balance of power, in Asia and perhaps across the globe, was forever altered with the establishment of the People’s Republic of China (PRC) in October of 1949. After two years of relatively small scale guerrilla warfare dating from 1947 in Vietnam, the conflict would now expand and become much more deadly. With the arrival of Chinese communist troops along the Sino-Vietnamese border, the inevitable end was in sight for the French in Vietnam. As General Giap would write years later, “This great historic event, which altered events in Asia and throughout the world, exerted a considerable influence on the war of liberation of the Vietnamese people. Vietnam was no longer in the grip of enemy encirclement, and was henceforth geographically linked to the socialist bloc.” 
Understandably enough Ho and the Viet Minh wasted no time in sending representatives northward to ask for support and assistance from the new communist government. Diplomatic recognition would be granted to the Democratic Republic of Vietnam (DRV) in January of 1950 by the PRC, the first nation to do so, followed soon by Stalin and the USSR also granting recognition.  Stalin, as the senior member of the communist firm, had informed Mao during meetings in Moscow soon afterwards that providing support and assistance to the Vietnamese struggle was a responsibility, and financial obligation, of the Chinese and the PRC.  This would not be an obligation that the Chairman would shirk from, far from it, he would honor Stalin's wishes and support the Vietnamese communist cause for the next 25 years. Mao would see Vietnam as one of three areas of Western imperialism bordering on China that threatened the PRC, the other two areas being Taiwan and Korea. Additionally Mao sincerely believed in supporting “national liberation movements in colonial nations” and fancied himself as the champion of non-European peoples across the globe. 
For the USSR and Stalin it was a low risk gamble. Its allies, the Chinese under Mao, and the Koreans and Vietnamese, could potentially tie down so much U.S. and Western strength in Asia that the global balance of power might shift, allowing the Soviets to strike westwards into Europe. Stalin discounted a Third World War and the west’s reaction since Germany and Japan were post-war shells, proclaiming “Should we fear this [world war]? In my opinion, we should not…If a war is inevitable, then let it be waged now, and not in a few years time.”  The die would be cast for warfare in Asia, and possibly elsewhere.
Chinese military support, 1950-54
In 1950 a classified U.S. Central Intelligence Report, CIA, stated that “The French position in Indochina is precarious,” somewhat of an understatement at the time.  The war had been going badly for the French and would only get worse. Ho would formally request military aid in the nature of equipment, advisors and training for the PAVN in April of 1950. Interestingly enough he would also request Chinese commanders at the regimental and battalion level to assist the Vietnamese Army, a request wisely denied by China, who would send advisors, not commanders to the North of Vietnam.  Such a request for Chinese commanders of PAVN units highlights the leadership problems present at the time in the Vietnamese forces, and the prevailing lack of confidence in Vietnamese commanders.
Chinese Military Advisory Group
After this request by Ho, the PRC in April of 1950 would begin forming the Chinese Military Advisory Group (CMAG) in order to provide military assistance to the Vietnamese forces fighting the French. General Wei Guoqing would lead the CMAG to North Vietnam, along with Senior General Chen Geng, the “scholar general,” and the PRC ambassador. The Second, Third and Fourth PLA field armies were directed to select experienced officers for service in Vietnam. Some 281 officers were selected with many having command experience. 
In June, two days after the start of the Korean War, as the powerful North Korean Army crossed the 38th parallel, the Chairman spoke with his military advisors enroute to Vietnam, “It is President Ho chi Minh who has asked me for [your assistance], Who would have thought our revolution would succeed first? We should help them. It is called internationalism. You will help them to win the battles after you get to Vietnam.”  The advisors of the CMAG would do exactly that as the impact of these Chinese advisors and new weapons for the PAVN would soon be apparent in the war. Standard Chinese Maoist doctrine for revolutionary wars would be stressed and advisors were informed to avoid the “mentality of big-state chauvinism and not to display contempt for the Vietnamese.”  By 1950 the French had almost completely lost control of the border region with China with isolation garrisons in Cao Bang and Langson struggling to maintain a presence.
The border region would be the first test of the new Chinese trained and equipped PAVN forces. General Chen Geng wrote in a report that “Some Vietnamese crack units are in high morale after receiving training and equipment in Yunnan and Guangxi, but Vietnamese cadres above the battalion level lack command experience in actual combat.”  This was an accurate statement concerning the PAVN but it was one problem about to be corrected.
The CMAG would provide planning guidance, among other things, for the upcoming Border Campaigns of 1950. This campaign would begin in September with garrison after garrison falling to the Viet Minh in the north with tremendous losses for the isolated French garrisons near the Sino-Vietnamese border. Outnumbered 8 to 1 by the Vietnamese, the French would lose immense amounts of men to include 6,000 of 10,000 men in the north, and supplies to include 13 artillery pieces, 125 mortars and 450 trucks, in what some have described as the greatest defeat in French colonial history since the French and Indian War in North America. 
Within 48 hours after these successful assaults on those isolated French outposts in the north, Chinese General Chen would hold what we would call today an after action review. Chen would brief Giap and other high ranking officers for four hours on the shortcomings of the Vietnamese Army. These short comings according to Chen would include not following the order for battle and attacking late, commanders not leading assaults from the front, poor communications, and cadres making false reports to superiors. One wonders how such criticism was received but such reviews are vital for an army’s subsequent growth and improvement. To General Giap “The victory shows Mao’s military thought was very applicable to Vietnam.” 
In addition to the training and planning guidance by the CMAG the logistical support from China began to increase steadily. The support provided was only 10-20 tons a month in 1951, increasing to 250 tons a month in 1952, further increasing to 600 tons a month in 1953 and 1,500 to 4,000 tons monthly during the last year of the war in 1954.  Additionally the Chinese transportation network to include roads and railways leading from China to Vietnam was improved also with some 1,000 trucks provided to the PAVN. This military aid provided by China enabled the PAVN to expand into a well armed and trained conventional force capable of defeating the French Army in large scale offensive operations. From a force in 1950 of 3 divisions the PAVN would expand two years later into a force of 7 divisions. All in all the Chinese military aid would arm a total of over 7 PAVN divisions. All this military support would not go unnoticed by the west, with the CIA, by March 1952, estimating that some 15,000 Chinese Communists were serving in Vietnam in various “technical, advisory and garrison capacities” with the PAVN against the French.  The Vietnamese Army now was a lethal force well equipped with small arms, machine guns, heavy 120mm mortars and 105mm howitzers, in addition to 20 and 40mm anti-aircraft guns. 
Decisive battle of Dien Bien Phu
By 1954 “Giap and the Chinese had built a tough, well-equipped, experienced, and dedicated army-a tool awaiting a great task and a master craftsman.”  The great task would be the decisive battle of Dien Bien Phu in western Vietnam near Laos, a battle that would end the First Vietnam War and the French presence in Indochina. Evidence suggests that the Vietnamese leadership did not see the opportunity provided by the French reoccupation of the valley until Chinese advisors alerted the Vietnamese, who initially wanted to move through Laos to invade South Vietnam, until convinced otherwise by General Wei Guoqing.  Additionally the CMAG would provide the Viet Mihn with a copy of the Navarre Plan, outlining French goals and objectives by the new French Commander in Vietnam.
With the signing of the Korean Armistice in July 1953 China could and would shift additional resources to Vietnam. Specific support provided for the Dien Bien Phu campaign would include planning, logistics, engineering advisors, trucks, rocket and 75mm recoilless rifle battalions, and Soviet Katyusha Rocket Launchers or “Stalin Organs.” A combined headquarters was established as the Dien Bien Phu Campaign Command with General Giap as Commander in Chief with Chinese General Wei Guoqing as General Advisor. 
Giap wrote years after the battle that “I felt there needed to be a meeting with the head of the team of friendly military experts who was also present. Generally speaking, relationships between us and friendly military experts ever since the Border Campaign had been excellent. Our friends had given us the benefit of their invaluable experience drawn from the revolutionary war in China and the anti-US war in Korea.”  It is interesting that in his account of the battle Giap makes no mention of Chinese material support or advice and planning assistance provided throughout this decisive last battle of the First Vietnam War. The Chinese advisors, such as General Wei Guoqing, are not identified or given any credit by Giap. Perhaps this is understandable given that one of the Chinese advisors would write later that “The greatest shortcoming of the Vietnamese Communists was their fear of letting other people know their weaknesses. They lacked Bolshevist self-criticism.”  The siege of Dien Bien Phu was to last 8 weeks with China providing 8,286 tons of supplies, including 4,620 tons of petroleum, 1,360 tons of ammunition, 46 tons of weapons and 1,700 tons of rice from supply depots 600 miles away. 
Chinese advisors would be involved at all levels during the battle including digging in the all important Vietnamese artillery into shellproof dugouts, experience learned the hard way in the hills of Korea.  In effect the battle of Dien Bien Phu would be planned and assisted by Chinese advisors and fought with Chinese trained, equipped, supplied, transported and fed PAVN troops in a military soup to nuts manner. This support is rarely mentioned as a contributing factor to the Vietnamese victory in 1954 but should be acknowledged in analyzing the battle.
Post-war support, 1955-63
In 1954, with the ending of the First Vietnam War, and the Big Power Geneva conference, Vietnam would be split into two nations, North and South Vietnam. In the north Ho and the party’s attention would be focused; at least for several years, on consolidating power and economic development. The inevitable Communist collectivization and tribunals began with confiscations, arrests, localized uprisings and the execution of 15,000 Vietnamese before order could be restored by the PAVN.  The CMAG returns to China in September of 1955 having accomplished its mission, quite possibly one of the most successful advisory missions ever. 
China would continue; however, to provide substantial levels of military aid for North Vietnam to the tune of $106 million from 1955 to 1963, effectively giving the North the resources needed to begin the insurgency in the South.  Thus, the North Vietnamese would form the National Liberation Front, NLF, in December of 1960 and the People’s Liberation Armed Forces, PLAF, the following year in 1961. Both the NLF and PLAF would be more commonly referred to as the Viet Cong, or Vietnamese Communists. 
A campaign of terror and assassination against the South Vietnamese government would soon begin as thousands of officials would be killed or kidnapped by Viet Cong insurgents.  The United States would not sit idly by during this period but began an ambitious program of military aid to the fragile government of South Vietnam. The stage was set, for a second war in Vietnam which would be, once again, fought largely with Chinese military aid.
Second Indochina War, 1964-75
The catalyst for the Second Vietnam War would be the controversial Gulf of Tonkin incident in August of 1964 between the U.S. Navy and North Vietnamese torpedo boats in the China Sea.  Perhaps convinced by President Johnson’s own words that election year that he would not expand the limited war in Vietnam by bombing the North or “committing a good many American boys to fighting a war that I think ought to be fought by the boys of Asia,” the North continued its attacks. Now with U.S. aircraft striking targets in North Vietnam the liberation war paradigm changed. The incident greatly alarmed both the Vietnamese and Chinese Communist leadership and caused both to move closer together in responding to increased U.S. military actions in Southeast Asia. China took immediate steps to move forces south towards the border with Vietnam and sent MIG jet aircraft to Hanoi to bolster the DRV’s defensives. Perhaps due to several factors, to include possible concern over Chinese intervention, the United States would gradually adopt a strategy of attempting to limit the war in Vietnam, or gradualism, not applying the maximum force possible towards defeating an enemy on the battlefield.  To the north Chairman Mao remained concerned about the U.S., in his opinion “the most ferocious enemy of the people of the world.”  Thus, when senior North Vietnamese leaders, to include General Giap, formally requested Chinese military aid in April of 1965, the response would be swift and sure. The PRC President would tell the Vietnamese that the Chinese people and party were obligated to support the North and therefore “…we will do our best to provide you with whatever you need and whatever we have.” 
Support requested and provided
The most immediate need was for anti-aircraft artillery, units to counter the overwhelming American air power over North Vietnam. Ho would request Chinese AAA units during a meeting with Mao in May of 1965 and PLA forces would begin flowing into North Vietnam in July of 1965 to help defend the capital of Hanoi and the transportation network to include railroad lines and bridges. This movement of troops from China was not lost on the U.S. as reported in a Top Secret CIA Special Report which identified seven major PLA units in North Vietnam to include the 67th AAA Division, and an estimated 25,000 to 45,000 Chinese combat troops total.  Recent Chinese sources indicate that this PLA AAA Division did indeed operate in the western area of North Vietnam.  In addition to AAA forces the PLA also provided missiles, artillery and logistics, railroad, engineer and mine sweeping forces. These forces would not only man AAA sites but would also build and repair Vietnamese infrastructure damaged or destroyed by U.S. airstrikes.  Such units would have quite a bit of repair work to do given that there would be more than a million tons of bombs dropped by U.S. aircraft upon North Vietnam from 1965 to 1972.  The Second Vietnam War would drag on for years as a sort of operational stalemate existed in the skies over North Vietnam. The U.S. could and did bomb the North at will, but the sheer numbers of Chinese forces, to include a total of 16 AAA divisions serving with a peak strength of 170,000 troops attained in 1967, would ensure that a high price would be paid by U.S. pilots with targets often rapidly rebuilt after destruction.  Chinese engineering and logistics units would perform impressive feats of construction throughout their stay in North Vietnam effectively keeping the transportation network functioning.
The U.S. Air Campaign over North Vietnam would thus be somewhat of a lost cause, not significantly hurting the communist North enough for Ho and the senior leadership to contemplate ending the insurgency in South Vietnam. Chinese troops in North Vietnam would eventually withdraw, for the most part, by 1970 as the Sino-Vietnamese relationship began to sour over the Paris Peace Talks, and the USSR, among other things. In addition to the AAA umbrella over the North, China would also provide the sinews of modern war that would enable the North Vietnamese Army to undertake modern, large scale offensive operations against South Vietnam in both 1972 and 1975. Chinese trucks, tanks, Surface to air missiles, MIG jet aircraft, 130mm artillery pieces, 130mm mortars, and shoulder fired anti-aircraft missiles, were all moved south. The PAVN had enough first class material to launch a 20 division mechanized Easter Offensive in 1972 into South Vietnam, more divisions than ever commanded by General Patton in Europe during World War II, as one American Officer would point out.  The North Vietnamese would pay a terrible price for this gamble, thanks to U.S. airpower and advisors on the ground, losing an estimated 450 tanks and over 100,000 troops killed in action during the 1972 offensive.  China would, again, make up for much of the PAVN equipment lost, after the Paris Peace Treaty was signed, in 1973 and 1974, enabling the North Vietnamese to reconstitute units for another offensive in 1975. U.S. forces would not be present this time to help its South Vietnamese allies as 18 well trained and equipped PAVN divisions rolled to Saigon in April of 1975, effectively ending the Second Vietnam War.  Both Vietnam Wars, from 1946-1975, ended in victory for North Vietnam against the west, but without the massive amounts of military aid provided by the PRC, most likely the outcome would have been different. As with all what-if’s of history we shall never know.
Analysis of support
“So the more troops they send to Vietnam, the happier we will be, for we feel that we will have them in our power, we can have their blood…They will be close to China…in our grasp. They…will be our hostages.” 
- - Chou En-lai speaking to Nasser, 1965
So how does one analyze the considerable military support provided by the PRC for the DRV during the 25 year period from 1950-1975, encompassing both the First and Second Vietnam Wars? Was the military aid provided, to include equipment, advisors and planning assistance, decisive in both conflicts or would the North Vietnamese have prevailed without this Chinese military support? In retrospect it seems clear that the Chinese military support for the DRV would be crucial. This Chinese support would be, in many respects, timely, appropriate and helpful without doing the job that the North Vietnamese needed to do themselves; that is, fight and win on the ground in South Vietnam. The PRC would not conduct an intervention on the scale that it conducted in Korea, avoiding the international perception of acting in the traditional China/tributary state relationship with Vietnam, all the while providing the tools and assistance required to “tip the scales” in both conflicts against the West. The People’s Republic would be, in effect, the world’s largest unsinkable aircraft carrier and army base, a strategic advantage that Western nations thousands of miles removed from the fighting could not hope to match.
As a biographer of Chairman Mao would remark “It was having China as a secure rear and supply depot that made it possible for the Vietnamese to fight for 25 years and beat first the French and then the Americans.” 
The numbers would be impressive enough, of the military equipment and supplies provided by China. According to Qiang Zhai, during the period 1950-54, the PRC would provide enough weapons, 116,000 small arms and 4630 artillery pieces, to equip some 5 infantry divisions, one heavy engineering and artillery division, one direct fire anti-aircraft artillery regiment and one guards regiment.  This infusion of equipment for almost seven divisions worth of troops could not, and would not, be matched by the French. As one U.S. military officer would comment years later “The French politicians continued their irresolute, incoherent, and penny-pinching support of military operations in Indochina, while demanding ‘decisive solutions.’”  The numbers would be even more impressive in the Second Vietnam War. Chinese support provided would increase by a factor of ten with arms and equipment from uniforms to tanks to small arms on a yearly basis greater than the entire military aid provided in the early 1950’s against the French.  Additionally the Chinese anti-aircraft artillery troops, peaking at a total of 17 divisions and 150,000 men in 1967, would claim credit for downing 1,707 U.S. aircraft over North Vietnam.  These Chinese combat troops who were not to be used south of the 21st parallel in North Vietnam; however, the presence of these units secured the North’s rear, turning the nation into the most heavily defended area in the world, and allowing the DRV to use resources in South Vietnam and elsewhere that would have been devoted to homeland defense.  In effect the U.S. would not be able to open a second front over the skies of North Vietnam, as it had been able to so successfully over Germany in the Second World War, due to these Chinese divisions.
But the mere presence of China to the north would also be a constant “sword of Damocles” hanging over the heads of Western and South Vietnamese nations. This nearness would also ensure that the ever present possibility of massive, full scale Chinese intervention would always be a factor that had to be considered by Western political and military leaders. Any plans for taking the fight to the North Vietnamese enemy on his home field by going north could not be seriously considered given the clear warnings by the PRC that it would intervene with massive force. The Chinese took great pains to communicate this willingness to fight on behalf of North Vietnam, if seriously threatened, to the United States, communicating warnings via various channels to include ambassadorial talks in Poland, third-party leaders such as the Pakistani and Tanzania Presidents and the British ambassador in Beijing.  In some respects this pledge of assistance was just as valuable as the tanks, trucks and guns provided by the PRC.
“Why have the Americans not made a fuss about the fact that more than 100,000 Chinese troops help you building the railways, roads and airports although they knew about it?” 
- - Chairman Mao to Vietnamese Premier Dong, 1970
In conclusion, as we can see from the considerable historical material outlined above, the military support provided by the People’s Republic of China, to include advisors, equipment and combat troops, was the decisive factor for the Communist Democratic Republic of Vietnam prevailing during 1949-1975 in both the First and Second Vietnam Wars. The small arms, mortars, ammunition, uniforms, tanks, artillery, radars, anti-aircraft guns, jet aircraft, trucks, and naval vessels were critical in the North Vietnamese struggle. However, what was even more critical and normally not acknowledged in the laundry list of war material is the psychological and strategic advantage provided by Communist China’s pledge to intervene in the advent of a United States invasion of North Vietnam, and communicating that pledge to the U.S. This strategic advantage in effect cannot be overstated.
As General Westmoreland’s former G-2, or Intelligence Officer would write after the Vietnam Wars “With a friendly China located adjacent to North Vietnam, there would have been little chance for a Vietnamese victory against the French, and later against the Americans and South Vietnamese.”  It is rather ironic that most professional historians tend to downplay or ignore China’s decisive role in North Vietnam’s victory while the military and intelligence communities, U.S. at least, are much more willing to acknowledge this fact. Perhaps this is understandable since if one acknowledges the role played by China it calls into question such Vietnam myths as the “poorly armed guerrilla” and the “military genius” of Giap, among other issues. Historians such as Xiaoming Zhang and Qiang Zhai are challenging the paradigm of accepted Vietnam history and in doing so are performing a great service.
“Thus the highest realization of warfare is to attack the enemy plans;” according to the learned military theorist Sun-Tzu in the Art of War.  In respects this is exactly what the North Vietnamese, and Chinese did in both Vietnam Wars: they successfully attacked the Western powers war plans. The considerable support for the DRV by the PRC, to include a promise to intervene with massive numbers of troops in the event of an invasion of North Vietnam, effectively eliminated this course of action, and perhaps others, as potential war winning options for the West. Thus, with the support of China, on a strategic level of war the DRV was able to remain upon the offensive throughout the war, maintaining the initiative and finally achieving victory as Saigon fell in April of 1975.