The Brigade can trace its roots to the formation of the Wessex Division in 1908.  It has had a turbulent existence and was fully mobilised and expanded to Divisional size for both world wars.  The Division was involved in conflicts in Mesopotamia, India and Palestine during World War One.  In World War Two it landed as part of Operation Overlord in Normandy during 1944.  43 (Wx) Division was involved in the breakout from Normandy and took a key role in Operation Market Garden providing support to the Airborne Forces around Arnhem.  It was also involved in the clearance of the Roer Triangle and Reichwald; the crossing of the River Rhine and the advance northwards to take the Port of Bremen, finishing in Bremerhaven.

In 1985 43 (Wx) Bde was formed as one of the new one star Headquarters principally as a National Defence Brigade commanding the Territorial Army in the south west of England.  In 1995 the restructuring programme within UK saw an increase in the brigade's responsibility to include regional and budgetary aspects working to a new superior headquarters - 3rd (United Kingdom) Division.  The Strategic Defence Review of 1998 further increased the brigade's responsibility and, as from 1April 1999, it came under command of Headquarters 5th Division, and moved from Exeter to Bulford in September 1999 to establish the new HQ 43 (Wx) Brigade.  In 2007, the Brigade came under the command of Headquarters 4th Division.