On the outbreak of the First World War, the men of the division accepted liability for overseas service to relieve Regular troops for the fighting fronts.

[1] On arrival, the division's units were sent distributed to various peacetime stations across India, Aden and Burma to continue their training for war.

By early 1916 it had become obvious that the Territorial Divisions in India were never going to be able to reform and return to Europe to reinforce the Western Front as had been originally intended.

They were replaced in the brigade by the 4th and 5th (Cinque Ports) battalions of the Royal Sussex Regiment, both previously having been attached to the division for training.

Whitty, the 133rd Brigade was sent to France with the rest of 44th Division as part of the British Expeditionary Force (BEF), landing on 9 April 1940.

The brigade saw fighting in the St Omer-La Bassée area during the Battle of France (23–29 May) and retreated to Dunkirk, where they were then evacuated from on 30 May 1940.

[13] Back in the United Kingdom, 133rd Brigade was re-equipped and reformed in numbers as all units had suffered heavy casualties (5th Royal Sussex had suffered 354 casualties, nearly half their strength) and had to be brought back up to their War Establishment strengths with large numbers of conscripted men.

The 133rd Brigade was positioned in Southeast England to defend what 44th Division's commander, Major-General Brian Horrocks, regarded as 'the No 1 German invasion area, stretching from the Isle of Thanet to Dover and on to Folkestone'.

[15] In May 1942 the brigade was sent to North Africa with the rest of the 44th Division, now under Major-General Ivor Hughes, where it fought at the Battle of Alam el Halfa.