The Myth Of The Invincible Guerilla defies the evidence:
Before long it became conventional wisdom that the U.S. was incapable of handling irregular warfare. This was odd, as the United States had an enviable track record when it comes to defeating guerillas and irregular forces in general. Even Vietnam, which conventional wisdom counts as a defeat, wasn’t. The conventional wisdom, as is often the case, is wrong. By the time the last U.S. combat units pulled out of South Vietnam in 1972, the local guerilla movement, the Viet Cong, was destroyed. North Vietnam came south three years later with a conventional invasion, sending tank and infantry divisions charging across the border and conquering their neighbor the old fashioned way.
When the United States first got involved with Vietnam in the late 1950s, there was good reason to believe American assistance would lead to the defeat of the communist guerilla movement in South Vietnam. That was because the communists had not been doing so well with their guerilla wars. In the previous two decades there had been twelve communist insurgencies, and 75 percent of them had been defeated. These included the Greek Civil War (1944-1949), Spanish Republican Insurgency (1944-1952), Iranian Communist Uprising (1945-1946), Philippine Huk War (1946-1954), Madagascan Nationalist Revolt (1947-1949), Korean Partisan War (1948-1953), Sarawak/Sabah “Confrontation” (1960-1966), Malayan Emergency (1948-1960), and the Kenyan Mau-Mau Rebellion (1952-1955). The communists won in the Cuban Revolution (1956-1958), the First Indochina War (1945-1954), and the Chinese Civil War (1945-1949). The communists went on to lose the guerilla phase of the Second Indochina War (1959-1970). Guerillas make great copy for journalists. You know, the little guy, fighting against impossible odds. What we tend to forget (and the record is quite clear and easily available), is that these insurgent movements almost always get stamped out. That does not make good copy and the dismal details of those defeats rarely make it into the mass media or the popular consciousness.
The main problem with COIN (Counterinsurgency Warfare) is that the American armed forces take it for granted. U.S. troops have been defeating guerilla movements for centuries. Through most of American history COIN has been the most frequent form of warfare American troops have been involved with. But COIN has always been viewed as a minor, secondary military role. It never got any respect. The generals preferred to prepare for a major war with a proper army, not playing cops and robbers with a bunch of poorly organized losers.
Yeah, if you look at the RAND databases of terrorism and guerilla organizations (discussed in Terrorism is not about Terror), you find that very very few actually succeed in any of their objectives.