The Phoenix Project and Military service
My take on the military references in the book, as a veteran, has to do with Man, Machine, Method, Measure; and, with drilling.

The military is entirely other compared to civilian operational models. Setting aside the chain of command and the Military Justice systems; consider that the way any service member mops, waxes and buffs a floor is detailed in a procedure outlining what (exact) equipment is to be used, how it is to be calibrated, how the person is to operate said equipment and measures by which to determine compliance with the procedure. The same goes for brewing coffee, making Kool-Aid, or launching aircraft from a carrier deck.

Secondly the military runs "drills" constantly so emergencies aren't chaotic and reactive; they are methodical and responsive. Hence these would be recommended practices in a DevOps context. Practice well-documented and consistently executed procedures often to increase reliability and responsiveness in the face of the unknown.

In Phoenix project they apply both these practices to tame the chaos that Bill and the team have been subject to throughout the book.