Army Formations

The following tables give an outline of the formation and structure of the British Army within the First World War together with the comparison showing how the Australian Imperial Force was structured within the British Expeditionary Force. During WW1 the British had five armies responsible for the northern section of the Western Front, taking over from the French Army in the Picardy region northwards and into Belgium.

At the outbreak of the First World War in August 1914, the first Commander in Chief of the BEF was Field Marshal John French. After the failed offensive at the Battle of Loos in 1915, French was replaced as commander of the BEF by Field Marshal Douglas Haig, who remained in command for the rest of the war.

BEF Army Strengths and Structure (source Western Front Association)

Formations	Organisation	Strength	Made up of	Commanded by
	Army	85,000 +/-	Two corps + HQ + Army Troops	General or Field Marshall
	Corps	38,500	Two divisions + HQ + Corps Troops	Lieutenant General
	Division	18,179	3 brigades + HQ + Divisional Troops	Major General
	Brigade	4055	4 battalions + HQ	Brigadier-General
(sub-) units	Battalion	1007	4 companies + HQ	Lieutenant Colonel
	Company	227	4 platoons + HQ	Captain or Major
	Platoon	52	4 sections	Lieutenant
	Section	13	1 Cpl + 12 Ptes	Cpl/Sergeant

AIF Army Strengths & Structure (source Australian War Memorial)

Formations	Organisation	Strength	Made up of	Commanded by
	Army		Two or more corps	General
	Corps	30,000 or more	Two or more divisions	Lieutenant General
	Division	10,000 – 20,000	3 brigades	Major General
	Brigade	2,500 – 5,000	4 battalions	Brigadier (General)
(sub-) units	Battalion	550 – 1000	4 companies	Lieutenant Colonel
	Company	100 – 225	4 platoons	Captain or Major
	Platoon	30 – 60	4 (later 3) sections	Lieutenant
	Section	9 – 16		Cpl/Sergeant