[3] The brigade was composed as follows during the war:[4] Remaining active during the interwar period as the 1st (Guards) Brigade, the brigade, still part of the 1st Infantry Division, was sent to France in September 1939 during the Second World War as part of the British Expeditionary Force (BEF) and it later took part in the Battle of France in May–June 1940 and the subsequent Battle of Dunkirk and were evacuated to England, spending the next few years on home defence anticipating a German invasion of England.

Subsequently, the 1st (Guards) Brigade served on the Italian Front for the rest of the war under command of various divisions, seeing action in the Battle of Monte Cassino (where the brigade played a holding "hinge" role during Operation Diadem) and the Battle of Liri Valley in May 1944.

Two years later, as the British mandate over Palestine ended, the brigade and division returned to Egypt.

In October 1951, British forces pulled out of Egypt outside of the Suez Canal Zone, and later the brigade returned to the United Kingdom, though it was in Cyprus during the EOKA insurgency for a period in 1957–8.

[3] In 1968 the dispatch of the entire 3rd Infantry Division began to be planned, as part of the United Kingdom Mobile Force, to reinforce Allied Land Forces Schleswig-Holstein and Jutland (LANDJUT).

[6] By the mid-1980s the British Army force earmarked as part of the UKMF to reinforce LANDJUT had shrunk to the 1st Infantry Brigade, as it had become.