He was one of the army officers profiled in Rick Atkinson's book The Long Gray Line: The American Journey of West Point's Class of 1966, published in 1989.

[1]: 243 On 19 June 1967 during Operation Concordia 6 companies from the 3rd and 4th Battalions, 47th Infantry Regiment engaged the Vietcong in Cần Giuộc District and the command & control UH-1 Crocker was flying in was shot down by small arms fire and crash-landed in a paddyfield, they were rescued shortly afterwards by another UH-1.

During this tour he was superficially wounded by a sniper bullet to the head and later contracted Typhus which led to him being sent back to the U.S. for several weeks to recover.

[1]: 341–3 In late 1971 Crocker was transferred to the Seventh Army at Ferris Barracks, Erlangen, West Germany serving first as a Battalion operations officer and then commanding an infantry company.

[1]: 404–6 In mid-1974 Crocker attended Command and General Staff College and then graduate school at Duke University obtaining a master's degree in psychology and counselling.

[1]: 525 On 15 May 1985 he was seriously injured during a night parachute drop near the Canoochee River when he was blown into trees, suffering 12 broken ribs and a collapsed lung.