RA: Royal Artillery.
Race to the Sea: The attempt by both sides on the Western Front to outflank each other by racing ever further northwards, eventually reaching the sea.
Radetsky: Class of Austro-Hungarian Pre-Dreadnought ships.
RAF: Royal Air Force, the British air wing of the armed forces formed on April 1st 1918.
Rafale: French tactic of rapidly firing artillery at a specific area.
R ammunition: German grooved bullets intended to reduce stoppages.
Ragtime: Inefficient/Not of a soldierly standard.
Railway Artillery: Artillery pieces, usually very large, mounted onto railway carriages.
Rainbow Division: US 42nd Division.
RAMC: Royal Army Medical Corps.
RAN: Royal Australian Navy.
RAP: Regimental Aid Post.
Racquet Grenade: Bomb attached to a handle.
Rataplan: Machine gun fire.
RB: Rifle Brigade.
RBVZ: Russo-Baltic Waggon Factory, Russian manufacturer of aircraft.
RCAF: Royal Canadian Air Force.
RCN: Royal Canadian Navy.
RDF: Royal Dublin Fusiliers.
RE: In English Royal Engineers, in French the Foreign Legion, Régiment Etranger.
RE-7: British bomber aircraft from 1915-16.
RE-8: British multi-purpose two seater biplane.
Reading Your Shirt: Looking for lice.
Red Cap: Military police.
Redif: Turkish reserve of the second line.
Red Hat: Staff Officer.
Red Tab: Staff Officer.
Red Triangle Man: Slang for a YMCA officer.
Rednik: Bulgarian private.
Redoubt: Fortified strongpoint in a trench system.
Regiment de marche: French regiment created from battalions of different units.
Regina Elena: Class of Italian battleships.
Register: The trial shots taken when ranging artillery.
Renault Light Tank: The main French tank of the period, used as an infantry-support weapon.
Reparations: Compensation payments usually paid by the losing party.
Respirator: Gas mask.
Restanten: Germans who had deferred their service.
Revers: French parados.
Revetment: The strengthening of a trench wall.
RFA: Royal Field Artillery.
RFC: Royal Flying Corps, the air arm of the British army until 1918.
RFP: Retail Food Price Index.
RGA: Royal Garrison Artillery.
RI: ‘Remonte-Inspektion’, German War Ministry Remounts Department.
Riesenflugzeug: ‘Giant Aircraft’, large German bomber aircraft.
Rissaldar: Indian lieutenant of cavalry.
Rittmeister: German cavalry/train captain.
RM: 1. Royal Marines 2. Régiment de marche.
RMA: Royal Marine Artillery.
RMLE: ‘Régiment de marche de la Légion Etrangére’, French Foreign Legion provisional battalion.
RMLI: Royal Marine Light Infantry.
RMMC: Régiment mixte de marche de cavalerie.
RMO: Regimental Medical Officer.
RMT: Régiment de marche de tirailleurs.
RMZT: Régiment de marche de Zouaves et tirailleurs.
RNAS: Royal Naval Air Service, the air arm of the Royal Navy and independent from the RFC (Royal Flying Corps).
RNASAAC: Royal Naval Air Service Anti-Aircraft Corps.
RND: Royal Naval Division.
RNR: Royal Naval Reserve.
RNVR: Royal Naval Volunteer Reserve.
Rocade: Trench railway train.
Roland C-II: German armed reconnaissance/escort plane.
Roland D-Type: Series of German fighter planes.
Rondins: The logs used to build ‘corduroy’ roads.
Rooti gong: Long Service Medal.
Rosalie: French slang for a bayonet and bayonet attacking.
Rosiori: Romanian cavalry.
Rotmistre: Russian captain of cavalry.
Roulement: French for the rotation of front line and reserve units.
Route en rondins: French ‘corduroy’ road.
Royal Navy: The naval part of the British military.
Royal Sovereign: Class of British battleships.
RS: Royal Scots
RSF: Royal Scots Fusiliers
RSG: Royal Scots Greys
RSM: Regimental Sergeant-Major.
RTA: Régiment de tirailleurs Algériens.
RTO: Railway Transport Officer.
RTT: Régiment de tirailleurs Tunisiens.
RTU: Return to Unit.
Rum jar: Nickname for German mortar bombs.
Rumpler 6B: Germany fighter floatplane.
Rumpler C-Types: Series of German armed reconnaissance biplanes.
Runner: Soldier transporting messages by hand.
Russian Army Air Service: The air arm of the Russian army.
Russian Sap: A trench dug beneath the surface so as to hide its progress.
Russki: Nickname for a Russian.
RVF: ‘Revitaillement en viande fraiche’, fresh meat supply.