Not by the Book is a short memoir, leavened by above-average writing (Smith became a reporter and cartoonist after the war) and some humor, but ultimately slightly misleading. An ROTC cadet from Georgetown, Smith found himself funneled into the very bottom of the military intelligence apparatus. He was lucky. He had a "safe" job at the HQ of the Americal Division (later notorious for the My Lai Massacre), which was about the safest spot for a green Lieutenant to be I Corps in 68-69. Safe is of course relative, with regular rocket attacks, sapper infiltration, and Vietnam in general. Of Smith's friends, one lost an arm, one went insane, and one was imprisoned for raping a child.

The actual job was, well, bored with interludes of terror covers it well. First there was a lot of paper shuffling, where it turned out that captured document exploitation was being handled by one overworked Private who didn't and couldn't care about the difference between propaganda leaflets, diaries, and high-valued captured orders. Smith worked up something that got useful information down to the Combined Document Exploitation Center in Saigon and intelligence back up in less than a week. This system processed between 30,000 and 50,000 pages in his time with the Division, although never to the standards of Smith's COs. The bad part of the job were the interrogations, and separating out the handful of VC or NVA from the masses of innocent civilians caught up in battalion sweeps. With his broken Vietnamese, Smith could stumble through some of the interrogations. The ugly parts where when his CO assigned him to conduct interrogations in a abattoir of a field hospital, trying to get information out of wounded VC before they died. When Smith was rotated to his next assignment, this job was split across three officers to spare their minds.

There was plenty of Vietnam Chaos. Smith was assigned to lead a convoy of clerks and translators on Route 1 (The "Street Without Joy") so Division could demonstrate to Battalion that it controlled the vehicles. He was sent into a hot LZ to secure the vital intelligence of Vietnamese grave scrolls under the assumption they were secret Chinese orders. The entire "black list" of high value VC commanders in I Corps turned out to be bunk, because American typewriters lacked the diacritic marks to indicate Vietnamese tones. Smith also wound up in command of a Battalion Military Intelligence Team nicknamed "The Dirty Dozen" because of their partying and black-market thieving. For the most part, they seemed like they were trying to do their job with a minimum of violence (some violence, as Smith and one of his subordinates both wound up beating a prisoner severely).

The best moment is Smith's description of "combat" during his convoy. He saw and heard his unit under fire, went for the radio, and regained his senses three hours later, everybody fine, nobody looking at him like he had been gibbering nonsense. No one else saw that they were under fire. But for three hours on a dangerous mission, Smith was commanding purely by reflex and no one noticed. The mind plays tricks.

The book closes with some simple lessons learned, which were promptly ignored. The best "simple" interrogation technique (as far as any of this is simple) is to demonstrate to a prisoner that you already know everything, so it doesn't hurt if they give you a few more pieces. Interrogators need close access to order of battle info. Translators are unreliable, and the Army needs to get language capacity as close to the front lines as possible. Soldiers need to know what happens to prisoners, so they'll treat them correctly, which means that interrogators have to send reports back to capturing units. Currently, all HUMINT is classified unless otherwise specified, which means the people who need it most can't see it.