The 3rd Infantry Brigade was a Regular Army infantry brigade of the British Army, part of the 1st Infantry Division. Originally formed in 1809, during the Peninsular War, the brigade had a long history, seeing action in the Second Anglo-Afghan War, and during both World War I and World War II.
The 1st Division was formed during the Peninsular War in Spain and Portugal, part of the army commanded by General Arthur Wellesley, later 1st Duke of Wellington. In 1814, the 3rd brigade took part in the Battle of New Orleans, commanded by Lt. Gen. John Keane. It also took part in the Battle of Ali Masjid in November 1878 during the Second Anglo-Afghan War.
The 3rd Brigade was constituted as follows during the war:
Between the wars the brigade, now redesignated 3rd Infantry Brigade, saw numerous changes in its battalions, including 2nd Bedfordshire and Hertfordshire Regiment, 1st Royal Scots Fusiliers, 1st King's Own Scottish Borderers and 1st Border Regiment. However, these were all posted away by 1937, either to other divisions stationed in the United Kingdom or to different parts of the British Empire. From 1936–1938 the brigade was commanded by Arthur Floyer-Acland In 1938 they were replaced by 2nd Buffs (Royal East Kent Regiment), 2nd Cameronians (Scottish Rifles) and 1st Royal Irish Fusiliers. There was no fourth battalion as it was in this year that British infantry divisions were reduced from twelve to nine battalions, infantry brigades reducing from four to three. These battalions, too, were replaced in early 1939, by 2nd Sherwood Foresters, recently returned from many years spent in British India and Guernsey, 1st Duke of Wellington's Regiment, returned to England from three years spent Malta, and 1st King's Shropshire Light Infantry, which had returned to England in 1938 for the first time after having served in British India in 16 years.
During the Second World War the brigade continued to be part of the 1st Infantry Division, and would remain with it throughout the war, and was sent to France on 25 September 1939, shortly after the outbreak of the war, and served as part of the British Expeditionary Force (BEF) in France. The brigade was to remain in France, serving alongside the French Army on the Maginot Line on the Franco-Belgian border until May 1940 when the German Army invaded Holland, Belgium and France and, during the fighting, forced the BEF to retreat to Dunkirk where the 3rd Brigade was evacuated to England, arriving on 1 June 1940.