Why did the North win the war in Vietnam?

I wondered about that question. If you think about the U.S. Civil War, for example, the answer is always given in terms of the larger population and superior industrial might of the North as compared with the South. So I wondered what the difference was in Vietnam during its war. It is surprisingly hard to find an answer on the Internet.

The industrial power of the two regions may not be of much importance, given that the weaponry was supplied in large part by the major powers fighting the cold war.

This interesting reference, published by the CIA itself, suggests that the forces arrayed against the government of the Republic of Viet Nam may have been equally divided between local insurgents and regular military, and much larger than was acknowledged by the U.S. military or U.S. intelligence at the time. This is a statement of the situation in the major report of 1968:

MACV, DIA, and CINCPAC still held enemy strength in South Vietnam to be between 280,000 and 330,000, he reported, whereas CIA now believed the figure to be somewhere between 450,000 and 600,000. Helms added that, of those totals, CIA accepted some 90,000 to 140,000 enemy irregulars, whereas MACV and CINCPAC still maintained that such forces could not and should not be quantified.

This is a fascinating document on the nature of information on which major decisions were made!

Also very worthwhile is "Revisiting Vietnam: Thoughts Engendered by Robert McNamara's In Retrospect" by Harold P. Ford. These are from his conclusions for intelligence officers:

5. There was no substitute for being immersed in the history, politics, and society of a region, in this case Indochina. The best analytic records were generally registered by those officers who had had considerable such exposure.

6. The ideal combination of such exposure was to have had experience both in the field and in Washington.

7. Those officers who best served CIA's purpose were those who went where the evidence on Vietnam took them, tried to tell it like it is, and did not precensor their judgments in order to sell them to higher authority known or believed to have strong contrary views of the question at hand.

8. Perhaps the central lesson for CIA officers which In Retrospect provides is the differing regard McNamara did or did not pay Agency judgments at different times. In short, his record and his book demonstrate the unhappy, eternal truth that intelligence is of use to decisionmakers primarily when it accords with their own views, or when they can use that intelligence to help sell their own particular policy arguments.

9. In sum, at least in the view of this author, the essence of Mr. McNamara's Vietnam policymaking and of America's fate in that war was captured years ago by a former West Pointer and former CIA Vietnam chief of station, Peer DeSilva: "[McNamara] simply had no comprehension of how the war should be handled. . . . Fundamentally we lost because we were arrogant, prideful, and dumb."

Read also "Unpopular Pessimism: Why CIA Analysts Were So Doubtful About Vietnam" by Harold P. Ford.

While you are at it, read "Limits to Interrogation: The Man in the Snow White Cell" by Merle L. Pribbenow. It bears directly on the interrogation procedures now in use in "the War on Terror".