On the outbreak of World War I the Territorial Force (TF) immediately mobilised for home defence, but shortly afterwards (31 August 1914), its units were authorised to raise 2nd battalions formed from those men who had not volunteered for, or were not fit for, overseas service, together with new volunteers, while the 1st Line went overseas to supplement the Regulars.

[4] By July 1916 the brigade was under the control of Northern Army of Home Forces, with the following units billeted across Essex:[3][4][5][6] The following were also attached to 8th Provisional Bde:[4] Late in 1916 the War Office decided to form three new home-service divisions and 72nd was the second of these, assembling in Somerset in November.

In May 1917 the 72nd moved again, to East Anglia With its HQ at Ipswich, the division formed part of Southern Army of Home Forces, and was responsible for the coastal defences from the River Deben to Orford Ness.

Henceforth part of the role of the Home Service divisions was physical conditioning to render men fit for drafting overseas, alongside units of the Training Reserve.

[54] Between July and September 1917, six Graduated Battalions replaced other units in 72nd Division, and in October these were affiliated to line regiments and adopted territorial designations.