Hi there!

I've written plenty about the military aspect of the defeat and the why's out of a counterinsurgency focus. You can read the longest answer here.

Now, as I mentioned, this is merely the military aspect and does discount other factors in the American defeat (US politics, lack of support at home and South Vietnam issues also playing a big role).

I'd also like to mention that there has been some dissenting voices about my above assessment of what led to the American military defeat in South Vietnam. Historian Gregory Daddis in his book Westmoreland's War: Reassessing American Strategy in Vietnam (Oxford University Press, 2014) argues that the US military command as well as its regular officers were familiar and had studied counterinsurgency extensively in the pre-Vietnam years and that the defeat in Vietnam was not because of the lack of counterinsurgency but rather because the American strategy in Vietnam (yet, Daddis argues, still with a very prominent focus on counterinsurgency) and the political goals were difficult to achieve since they were hard to properly define into achievable goals. Daddis also puts out an argument regarding how detrimental the South Vietnamese government was to the American war effort in South Vietnam.

While it is fair to say that the works of French counterinsurgency theorists like David Galula were studied by Americans, his books were only published in 1963 and 1964 respectively and were too late to have much of an impact. More importantly, I disagree with Daddis argument since there is little proof of a widespread familiarity with practical counterinsurgency (despite being taught) and the few observers involved in some of the counterinsurgency conflicts of the post-war world drew entirely wrong lessons. For example, during the Greek Civil War, US observers saw the Greek government victory in the war as the result (and evidence thereof) of conventional power, thus misreading the conflict entirely since it had been the insurgents mistake to commit themselves to final, fixed position. Vietnamese insurgents would not be as kind to concentrate their entire force in a conventional position like the Greek communists. But what about practical experience? There were some involvement in counterinsurgency during the Korean War but this left very little to no impression. Beyond that, the last time the United States Army was involved in counterinsurgency was in 1902! (as opposed to the USMC who had last been involved in counterinsurgency throughout the three first decades of the 20th century).

Other points that Daddis makes are equally unconvincing (if counterinsurgency was indeed a major part of American strategy, then why wasn't more time spent on it as opposed to the large divisional offensives?), but he still makes a very important point regarding the political goals set out by the American government. There also seem to be a will in Daddis to make a scapegoat out of South Vietnam which seems rather unfair. The book as you can imagine has created some controversy amongst Vietnam War scholars with some praising it and some being far more critical than yours truly, yet it is books like these which challenges and drives this area of study further.

My friend, I think you mean guer--

• dat username

Oh ho, I see what you did there. Well played.

Anyways, to answer your question--bluntly stated, the US did have a sizable amount of counterinsurgency experience from the US-Phillippine war. However, the American military ended up being unprepared due to a variety of factors and miscalculations.

David Halberstam, though not an historian, offers up some explanations for this. In The Best and the Brightest, he implies that since America had fought another war in Asia more recently, i.e Korean in the 1950s, several influential generals thought the war in Viet Nam would be more similar to the Korean War than the counterinsurgency of the Philippine War, more than half a century ago. As Halberstam says on page 172 of my book, "There was a paralell war: the French Indochina war or the Philippine insurrection. But Taylor made the comparison with Korea, and if the general, who was so widely respected, a man who was an intellectual and quoted Thucydides, did not see this crucial nuance, who else would?"

Anthony James Joes would seem to concur with this, though he takes more of a tactical-level view. On page 63 he states, "Since World War II, successful campaigns against guerillas in Greece, Malaya, the Philippines, South Korea, and Algeria all involved the combination of mobile strike forces and territorial controlm which is the essence of the clear-and-hold strategy. The Pentagon Papers made it clear that many policy makers and planners understood proper methods of pacification and guerilla fighting but that allied forces in the field preferred massive airmobile operations and big sweeps. Few soldiers and little attention remained for clearing and holding--that is, protecting the civilian population--and this was the root of the allied failure to deal effectively with the insurgency."

So, OP, to answer your question, the U.S. had fought guerilla wars, quite a few in fact. The main example I used was the Philippine War, but we were aware of other counterinsurgency operations from other countries, and there were certain combatants in the American Civil War and the Seminole Wars who could be classified as irregulars, or guerrilla fighters. But for a variety of reasons, including some political ones Halberstam mentions but I didn't describe here (ask if you'd like to know more), the U.S didn't bring as much of that counterinsurgency knowledge to bear on the Viet Cong as it could have.

Sources Cited:

David Halberstam, The Best and the Brightest. New York: Ballantine Books, 1992.

Anthony James Joes, The War for South Vietnam, 1954-1975, Revised Edition. London: Praeger, 2001.