1900 - 1930's era Pre WW1 and up to the beginning of WW2
1st Army
A - Z Units
Aero
Armies
Corps
Divisions
Enlisted
Regiments
Cavalry
Aero Squadrons - Aviation
Ambulance
Artillery
Cavalry 1, 2-Cav MG Units
Chemical Corps
Engineers
Gas and Flame Units
Headquarters R-Unassigned Personnel
Infantry
Interpreter - Intelligence Police
Machine Gun Units
Medical Units
Motor Transport Corps
Pioneers
Provost Marshal (MPs)
Quarter Master Units
Railway Artillery Units
Sanitation Units
Signal Units
Tank Corps Units
Trench Mortar Units
2nd Army
Balloon Pilots & Ground Personnel
2nd Army - 6th Aero Park
4th Corps Elements
Aero Units
3rd Army
Aero Personnel
Intelligence Police
Garrison Cap worn by Intelligence Police personnel.
Army Corps 1st - 9th
1st Corps
2nd Corps School R-Patch King
2nd Corpsl
3rd Corps School Patch King
3rd Corps
4th Corps
5th Corps
6th Corps
7th Corps
9th Corps