The South Midland Division spent many months in England training until 13 March 1915 when it was warned to prepare for overseas service to reinforce the British Expeditionary Force (BEF) on the Western Front which had suffered heavy casualties in the winter of 1914-15.

In early November 1917 the 143rd Brigade, with the rest of 48th (South Midland) Division, was sent to the Italian Front and fought at Piave River in June 1918 and later at Vittoria Veneto, which ended the war in Italy with the signing of the Armistice of Villa Giusti.

The men of the brigade were called up for full-time war service and, with the division, began training in preparation for an eventual move overseas.

[10] The 143rd Infantry Brigade, commanded at the time by Acting Brigadier James Muirhead, a Regular Army officer, with the rest of the 48th Division was sent to France in early 1940.

The brigade arrived in France on 12 January,[11] where it became part of the British Expeditionary Force (BEF), which was stationed alongside the French Army on the Franco-Belgian border.

[12] Due to a policy within the BEF of integrating the Regular Army with the Territorials,[13] the 5th (Huntingdonshire) Battalion, Northamptonshire Regiment was sent to 11th Brigade of the 4th Division and exchanged for the 1st Battalion, Oxfordshire and Buckinghamshire Light Infantry, a Regular Army unit.

The brigade and division were successfully evacuated, yet had suffered extremely heavy casualties (8th Royal Warwicks had been reduced to 8 officers and 134 ORs) and had to be completely reformed and brought up to strength with conscripts.

[14][15] The brigade remained in this role for the rest of the war, supplying drafts of replacements for the divisions fighting overseas.

With the disbandment of 5th Division, 143 (West Midlands) Brigade came under the control of the new Support Command based in Aldershot, in April 2012.