, ▁the ▁T ank ▁Corps ▁of ▁the ▁United ▁States ▁Army ▁was ▁established ▁under ▁Colonel ▁S . D . ▁Rock en bach . ▁At ▁his ▁direction , ▁Lieutenant ▁Wh art on ▁designed ▁the ▁original ▁coat ▁of ▁arms : ▁a ▁triangle ▁on ▁a ▁shield ▁with ▁surrounded ▁by ▁a ▁w re ath ▁and ▁a ▁silver ▁drag on . ▁The ▁triangle ▁itself ▁is ▁an ▁old ▁her ald ic ▁element ▁of ▁arm orial ▁design ▁known ▁as ▁a ▁p ile , ▁representing ▁the ▁head ▁of ▁a ▁spe ar . ▁There ▁was ▁no ▁shoulder ▁patch ▁in ▁ 1 9 1 8 . ▁ ▁The ▁ 7 th ▁Caval ry ▁Brigade ▁( me chan ized ) ▁contributed ▁the ▁other ▁part ▁of ▁the ▁present - day ▁Arm or ▁shoulder ▁patch . ▁The ▁brig ade ▁formed ▁out ▁of ▁the ▁ 1 st ▁Caval ry ▁Regiment ▁in ▁Mar fa ▁Texas , ▁on ▁ 1 6 ▁January ▁ 1 9 3 3 ▁under ▁General ▁Van ▁Voor his , ▁then ▁Colonel ▁of ▁the ▁Caval ry . ▁The ▁ 7 th ▁Caval ry ▁Brigade ▁included ▁the ▁ 1 3 th ▁Caval ry ▁and ▁had ▁been ▁organized ▁specifically ▁to ▁develop ▁the ▁new ▁arm ored ▁force ▁concept ▁while ▁training ▁in ▁the ▁emer ging ▁modern ▁war - f ight ing ▁tact ics . ▁ ▁Colonel ▁George ▁Lin th wa ite ▁( then ▁a ▁newly ▁en list ed ▁Private ) ▁joined ▁the ▁ 1 3 th ▁Caval ry ▁regiment ▁in ▁ 1 9 3 3 . ▁Major ▁General ▁Robert ▁W . ▁G row ▁( then ▁a ▁Major ▁and ▁brig ade ▁adj