What's the best book on history of the Vietnam War?

I’d like to read just one book on the Vietnam War - a history, not a political diatribe for or against it or an analysis of how it changed our society, just a history of that period.

What is the one book that does this best?

Try “Vietnam at War: The History, 1946-1975” by Phillip Davidson

For a really brief overview, there is always “Vietnam For Dummies.” It is actually a fairly comprehensive overview, with pretty balanced documentation.

Vietnam: A History, by Stanley Karnow. This book covers the whole span of the war in a relatively manageable size. If you only have time for one book, I recommend this one.

Also worth reading is America’s Longest War: The United States and Vietnam, by George Herring. It is also a general history with a great bibliography.

I agree with Baby Fish Mouth - there is even a companion series of videos available for the work by Stanley Karnow.