US Army Ranger is a bay gelding with a white blaze bred in Ireland by Orpendale, Chelston & Wynatt, a breeding company associated with John Magnier's Coolmore Stud.

His other progeny include Cape Blanco, Frankel, Golden Lilac, Nathaniel, New Approach, Rip Van Winkle and Ruler of the World.

[3] Her three previous foals were Nevis (winner of the Lingfield Derby Trial), Stubbs (third in the Doncaster Stakes) and Words (Munster Oaks).

On his racecourse debut US Army Ranger contested a maiden race over ten furlongs on heavy ground at the Curragh on 3 April 2016.

Starting at odds of 15/8 he raced at the rear of the ten runner field before beginning to make steady progress at half way.

"[9] On 4 June US Army Ranger was part of a five horse O'Brien entry in a sixteen-runner field for the Epsom Derby and was made the 7/2 favourite ahead of Wings of Desire and Harzand.

[10] After a break of two and a half months US Army Ranger started favourite for the Royal Whip Stakes at the Curragh on 21 August but never looked likely to win and finished fourth of the seven runners behind the four-year-old Success Days.

In September he was made odds-on favourite for the Group Three Enterprise Stakes at Leopardstown Racecourse but was beaten half a length into second place by the filly Zhukova.