During the Boer War, the 5th Infantry Brigade, known as the Irish Brigade, fought in the Battle of Colenso under Major General Arthur Fitzroy Hart. It consisted of the 1st Royal Dublin Fusiliers, 1st Inniskilling Fusiliers, 1st Connaught Rangers, and the 1st Border Regiment. Following the end of the Boer war in 1902 the army was restructured, and a 3rd Infantry division was established permanently at Bordon as part of the 1st Army Corps, comprising the 5th and 6th Infantry Brigades. The brigade was part of the 2nd Division during the First World War and was one of the first British units to be sent overseas on the outbreak of war. The brigade became part of the British Expeditionary Force and saw action on the Western Front in the Battle of Mons and the subsequent Great Retreat and at the First Battle of Ypres, which saw the old Regular Army virtually destroyed. During the Second World War, the 5th Brigade was again part of the 2nd Infantry Division and was sent to France in 1939 shortly after the outbreak of war, where it joined the British Expeditionary Force. It served on the Franco-Belgian border until May 1940, when it was evacuated at Dunkirk after fighting in the short but fierce battles of France and Belgium in which the German Army nearly cut off the entire BEF from the French Army. With the division, the brigade remained in Britain on home defence until 10 April 1942, when it was shipped out to India to fight the Imperial Japanese Army after a series of disasters suffered by the British and Indian troops stationed there. The 5th Brigade served with the 2nd Infantry Division in the Burma Campaign under General Slim'sBritish Fourteenth Army and fought in the Battle of Kohima, which managed to help turn the tide of the campaign in the Far East.
Following the war, it was part of the British Commonwealth Occupation Force in Japan, and then the British Army of the Rhine until 1964, when the Brigade Group was released to bolster the strategic reserve. It arrived in Borneo in October 1965 to take control of the Mid West Sector during the Indonesia–Malaysia confrontation, but by 1968 it was back in the United Kingdom as part of the 3rd Infantry Division. It did a tour in Northern Ireland during the early part of the Troubles. In the early 1980s, the Field Force concept was dropped in favour of traditional Brigades; 5th Infantry Brigade was reformed at Aldershot in January 1982 by the redesignation of 8th Field Force. The Brigade consisted of the former elements of the Parachute Contingency Force from 6 Field Force, at the time 2 PARA, together with a second Parachute Battalion from 8 Field Force.
Following the Falklands War, it was converted into 5th Airborne Brigade. The brigade comprised the two battalions of the Parachute Regiment, together with additional parachute support elements and a small parachute deployable Brigade HQ. The 7th Parachute Regiment RHA returned from Germany and was converted to an airborne unit and attached to the brigade. A Brigade Logistic Battalion was formed. The 5th Airborne Brigade Order of Battle was as follows:
