The Volunteer Force of part-time soldiers was created following an invasion scare in 1859, and its constituent units were progressively aligned with the Regular British Army during the later 19th Century.

The Stanhope Memorandum of December 1888 introduced a Mobilisation Scheme for Volunteer units, which would assemble in their brigades at key points in case of war.

The assembly point for the brigade was at Caterham Barracks, the Guards' depot conveniently situated for the London Defence Positions along the North Downs.

[11] With the rest of the division, the brigade was destined to see service in the trenches of the Western Front for the rest of the war, seeing first action at the Gommecourt salient, fighting in late June/early July 1916 alongside the 46th (North Midland) Division in an diversionary attempt to distract the German Army's attention away from the impending Somme offensive.

The division also fought on the Hindenburg Line in March 1917, followed by the battles of Arras, Langemarck, Passchendaele (also known as Third Ypres), Cambrai (which saw the first use of large numbers tanks in warfare), Second battles of the Somme, Albert, and the Hundred Days Offensive, which saw the First World War eventually ending on 11 November 1918.

When most of the BEF was forced to retreat to Dunkirk during the disastrous Battle of France in mid-1940 the division assumed a defensive posture and alternated between coastal defence duties and training to repel an expected German invasion which never arrived, due mainly to events that happened in the Battle of Britain and the German invasion of the Soviet Union in mid-1941.

The 18th were posted elsewhere in mid-February 1941 and replaced by 10th Battalion, Royal Berkshire Regiment, another unit raised for war service, created in September 1940.

[30] The 168th Brigade and the rest of 56th Division, now composed largely of a mixture of pre-war Territorials, Regulars and wartime volunteers, moved to Suffolk in June 1942 where they were inspected by General Sir Bernard Paget, at the time Commander-in-Chief, Home Forces.

[40] The division, part of British X Corps and under command of Mark Clark's U.S. Fifth Army, had just seen fierce fighting in the Salerno landings.

[41][42] Shortly afterwards, on 30 January, the Commander of British X Corps, Lieutenant-General Sir Richard McCreery, was ordered to send a brigade to strengthen the Anzio bridgehead.

[44] The 168th Brigade landed at Anzio on 3 February[27] where, soon after arrival, the battalions were almost immediately thrown into battle as the Germans launched a counterattack and the London Scottish, as vanguard of the brigade and supported by Sherman tanks of the 46th Royal Tank Regiment,[45] launched their own spirited counterattack in an attempt to relieve the 3rd Brigade (1st Dukes, 2nd Foresters, 1st KSLI), of British 1st Division, which was surrounded, in what was known to both sides as the "Thumb", by Campoleone station and the lateral road, and was virtually cut off, taking heavy casualties.

The London Scottish, supported by 46th RTR, "fought their way forward over sodden ground under heavy German fire in a driving rain",[46] ending up some 400 yards short of the lateral road which shored up the right flank long enough to enable the 3rd Brigade to withdraw, under cover of nightfall, without further loss.

[48] In its first action at Anzio the brigade helped to repel a major counterattack, potentially saving the British 1st Division from destruction, in some of the fiercest fighting endured by soldiers of either side on the Italian Front thus far.

Indeed, Albert Kesselring, the Commander of the German forces in Italy "believed that the Fourteenth Army had overestimated the strength of VI Corps and that the attack should have commenced at least twenty-four hours earlier, before the arrival of the 168th Brigade".

The brigade had suffered 50% casualties,[53] the highest casualty rate of the three brigades of 56th Division, and was brought up to strength mainly with mainly ex-anti-aircraft gunners of the Royal Artillery who had been retrained as line infantry (most of whom were commented by officers to be of excellent quality as infantrymen), together with those many wounded returning from hospital.

To replace the Royal Berkshires was the 1st Battalion, Welch Regiment, a Regular Army unit which had already seen extensive service in the Middle East and Crete.

[55] While in Egypt the brigade was inspected by General Sir Bernard Paget, now Commander-in-Chief, Middle East Command.

The brigade was pulled out of the line on 21 September and due to the severe shortage of manpower, biting particularly hard in the Mediterranean theatre (all available replacements had been used up and although 5,000 ex-anti-aircraft gunners had been transferred to the infantry[59] to be retrained, they had yet to complete their training and would only be available in October), that plagued the British Army at this time, and the heavy casualties in the brigade (1st Welch only mustered 320 all ranks),[60] it was decided to disband two brigades (the other being 18th Infantry of 1st Armoured Division) to make up for the infantry shortage.