From the mid- to late-1950s, top U.S. officials in Saigon and Washington did not believe Ho Chi Minh’s Democratic Republic of Vietnam (DRV) would attempt to conquer South Vietnam through the formation of a rural-based insurgency. American officials came to this conclusion for a number of reasons. Most notably, during the final stages of the First Indochina War, a sizeable segment of the Vietminh military apparatus fought as conventional main forces, rather than as guerrillas. And these conventional Communist units, employing standard siege tactics, defeated the French at Dien Bien Phu. Furthermore, when the First Indochina War ended in July 1954, the Vietminh guerrilla units still in southern Vietnam began regrouping to the North. Once there, those guerrillas were integrated into the DRV’s conventional force structure. Although several thousand of the best-trained and motivated southern guerrillas remained south of the 17th parallel in violation of the Geneva Accords, a well-coordinated guerrilla army did not exist in South Vietnam in the 1950s.
Another reason the Americans didn’t believe the DRV would initiate a guerrilla war in South Vietnam had to do with the fact that throughout the decade of the nineteen fifties, North Vietnam expanded the ranks of its conventional army. That army was organized along Russian and Chinese lines, which included regular companies, battalions, regiments, and divisions. Its troops were also armed with Eastern Bloc and Chinese weapons and equipped with Russian trucks and armoured vehicles.
North Vietnam’s force structure, weapons, and tactical doctrine indicated that if it attempted to take South Vietnam it was going to do it with its conventional forces. As a result, the Americans concluded that the North’s conventional forces posed the greatest threat to the South. Based on that conclusion, the U.S. trained and equipped the South Vietnamese Army to fight a conventional war.
But in 1959, Ho Chi Minh, Le Duan, and Vo Nguyen Giap decided to wage a protracted guerrilla war, or “War of National Liberation” against South Vietnam. The Communists planned on toppling the Saigon regime of Ngo Dinh Diem and reuniting the country through a rural-based insurgency. Selective terrorism, political agitation, misinformation, and the infiltration of spies into the South Vietnamese government and military would augment the armed guerrilla struggle.
The Americans serving with the Military Assistance Advisory Group (MAAG) in Saigon were not entirely surprised that Hanoi’s leaders rejected a conventional war strategy. For starters, South Vietnam’s geography did not lend itself to an overland invasion from the north. A series of east-flowing rivers and steep east-running ridge lines in the northern and central provinces of South Vietnam, especially Hai Vann Pass north of Danang and the Thu Bon River at Hoi An, acted as major physical obstacles to an invading northern army passing down Vietnam’s coastal plain. And even if Communist forces successfully forded all the coastal rivers and overtopped the mountain passes, and that was a big if, they would still have been subjected to devastating and continuous bombardment from U.S. warships cruising in the waters just offshore in the South China Sea and from carrier-based aircraft. At a number of locations along the coastal plain, Route 1 (the primary line of communication for any invading Communist army) came within feet of the South China Sea. At those locations, the U.S. Navy would have slaughtered the exposed Communist troops attempting to pass down the highway. North Vietnam’s General Vo Nguyen Giap was well aware that U.S. naval and air forces would destroy his conventional army in the coastal plain – long before it ever reached Saigon.
The Korean War had taught the Vietnamese Communists several lessons. Specifically, during that earlier war, American airpower had taken a heavy toll on North Korean and Chinese supply lines and troop formations. The U.S.’s interdiction of southbound supplies and soldiers on the Korean peninsula had limited the offensive capabilities of the Communist armies arrayed against the Americans along the 38th parallel. This explained why the war became a stalemate after 1951. But unlike a conventional army, a guerrilla force, hiding amongst the peasants of South Vietnam and relying on those same peasants for supplies, would not be as susceptible to supply disruptions or attrition from American airpower.
Having consulted with Chinese and North Korean military officials during and after the Korean War, Hanoi’s leaders also recognized the potential for a U.S. Inchon-style landing behind the lines of a southbound North Vietnamese invasion force. If the North Vietnamese Army attempted to race down the coastal plain in tanks and trucks, U.S. Marines could land behind the advancing Communist army, cutting off its resupply and reinforcement. If that happened, then the North Vietnamese Army, like the North Korean Army at Pusan following the U.S. Marine landing at Inchon, would either have to rapidly retreat north or perish in the South. A conventional invasion down the coastal plain played to U.S. advantages – it invited Communist defeat.
The only other North Vietnamese invasion route into South Vietnam lay through Laos. Communist units could pass from North Vietnam into Laos via the Annamese Cordillera’s Mu Ghia and Ben Karai passes, slip past the western border of South Vietnam, and then turn east from Laos into South Vietnam, entering it through the highlands. This invasion route avoided U.S. naval power, lessened the likelihood of an Inchon-like landing behind Communist lines, and reduced the effectiveness of U.S. airpower, since the weather, terrain, and vegetation in the highlands afforded Communist troops cover and concealment from patrolling American aircraft. But in 1959, the Politburo rejected a conventional invasion of South Vietnam through Laos because neither a well-developed road network, nor a logistical base capable of supporting a conventional army, yet existed in the Laotian Panhandle.
Concerns about Western public opinion and the threat of massive U.S. military intervention in South Vietnam influenced Hanoi’s decision to pursue a war of national liberation. The DRV wanted Western public opinion on its side in its struggle against the Diem regime and its American supporters. Sympathetic progressive elements within Western society could pressure the U.S. government to forego direct military intervention in the conflict, just as they had during the First Indochina War when the Eisenhower administration considered direct American intervention to save the French expeditionary force trapped at Dien Bien Phu.
On the other hand, a highly-publicized cross-border invasion by masses of regular, uniformed North Vietnamese troops would likely turn Western public opinion against the Hanoi government. An invasion of the South would be perceived by many in the West not as an attempt to liberate the southern populace from a repressive regime, but as an act of blatant aggression. The DRV would earn the Western public’s condemnation, as had North Korea after its invasion of South Korea in 1950. Ho Chi Minh, who carefully cultivated a public image at home and abroad of a man of peace, would’ve been compared to Kim Il Sung or Adolf Hitler in the American and Western European media. Ho was aware that an overt invasion of the South might persuade otherwise disinterested states, such as Great Britain, to join the U.S. in the defence of South Vietnam.
The DRV wanted to isolate the U.S. in Vietnam, rather than take actions that garnered it allies. An insurgency, consisting predominately of rural, poor southerners, would look like a legitimate expression of popular discontent against the American-backed Saigon regime. The choice to pursue an insurgency in the South was as much a public relations strategy as it was a military strategy. A war of national liberation in the South had the potential of winning the Communists allies in the West, while a conventional invasion would win the U.S. allies.
In Korea, the United States responded massively to Kim Il Sung’s cross-border invasion of South Korea. Ho Chi Minh did not want the Americans doing in Vietnam what they had done in Korea. He desired very much to keep the U.S. from direct military intervention in Vietnam. A protracted guerrilla war had a much greater chance of discouraging U.S. military involvement than an outright invasion. A southern insurgency would conceal Hanoi’s role in the South, making it harder for the Americans to label the war as an act of aggression.
Furthermore, the Americans would find it difficult to brand an insurgency as Communist aggression if the lion’s share of guerrilla supplies, foodstuffs, and recruits originated within South Vietnam. Just as importantly, if the U.S. did intervene on the ground in the South, Ho and his colleagues believed the high-tech, road-bound American forces would have difficulty defeating a guerrilla army. Trained to fight a conventional war in Western Europe, U.S. troops would readily defeat a conventional army in the South, but an insurgency would present the U.S. with a whole host of problems, especially trying to determine friend from foe.
Finally, Hanoi calculated that the insurgency’s indigenous, popular character might dissuade the United States from committing its own ground troops to the suppression of the will of the South Vietnamese people. It was one thing for the Americans to defeat an invading Communist army; it was something altogether different, and morally ambiguous, for the United States, which professed to be the world’s foremost defender of Democracy and personal choice, to combat a “People’s War” supported by the peasant masses.