Armed Forces
Specific armies are capitalised – British Army – but not when used generically, as in army, navy, air force. Ranks are always capitalised – Sergeant, Admiral, Lieutenant and so on.
Should armed forces be Capitalised?
Formal names of military units, including armies, navies, air forces, fleets, regiments, battalions, companies, corps, and so forth, are proper names and should be capitalized.
Should British military be capitalized?
Full names of armies, navies, air forces, etc., are capitalized (U.S. Marine Corps, Royal Air Force, the British Navy, Army Corps of Engineers). The words army, navy, etc., are lowercased when not part of an official title.
