The division was to have been part of a proposed Commonwealth Corps, formed for a planned invasion of Japan in 1945–46, and later served in the British Mandate of Palestine.

[14] According to Picton, the fighting by the 3rd was so intense at the Battle of Vitoria, that the division lost 1,800 men (over one third of all Allied losses at the battle) having taken a key bridge and village, where they were subjected to fire by 40 to 50 cannons, and a counter-attack on the right flank (which was open because the rest of the army had not kept pace).

[21] The 3rd Infantry Division, under the command of Major-General Bernard Montgomery was sent overseas to France in late September 1939, just under a month after the outbreak of the Second World War.

[22] There the division became part of Lieutenant General Alan Brooke's II Corps of the British Expeditionary Force (BEF).

41 (Royal Marine) Commando, with 5th Royal Marine Independent Armoured Support Battery (Centaur IV close support tanks), and specialist units of the 79th Armoured Division: 22nd Dragoons (Sherman Crab mine clearing tanks), Royal Engineers 77 and 79 Assault Squadrons of 5th Assault Regiment (Churchill AVRE tanks for obstacle demolition).

6 Beach groups under command for the assault phase: these included additional engineers, transport, pioneers, medical services and vehicle recovery sections which would hold and manage the beach landing area after the initial assault.

During the often intense fighting from Sword Beach to Bremen, the 3rd Division suffered 2,586 killed with over 12,000 wounded.

After spending time in Egypt and undertaking internal security operations during the Jewish insurgency, it was disbanded in June 1947.

[39][40][41] With the outbreak of the Korean War and the need for a divisional-sized strategic reserve based in the UK, the 3rd Infantry Division was reformed at Colchester, England, on 14 December 1950.

[41] During this period, the Egyptian government abrogated the Anglo-Egyptian Treaty of 1936, which was the basis for British troops to remain in the canal area.

The ensuing political landscape saw increased animosity to the British presence, eventually resulting in an agreement to withdraw.

[42] The division departed for the UK during 1954, where it returned to Colchester and its role as the British Army's strategic reserve.

In the event of a successful invasion, the division would have severed as a follow-up formation and occupied Port Said.

[40][43] In 1961, elements of the division were dispatched to Kuwait to deter an Iraqi invasion; signals personnel were sent to assist with the British Cameroons referendum; and other troops were sent to Kenya.

[44] On 1 April 1968, the Army Strategic Command was formed in the UK, with a goal of supporting NATO forces from as far north as Norway to as far south as Turkey; to provide internal security operations world-wide; and to undertake limited operations in conjunction with allies.

The 3rd Division was assigned to this command, and from 1969 onwards was the primary British formation that would reinforce European-based NATO forces in the event of the Cold War heating up.

Under Operation Banner, the division also deployed troops to Northern Ireland for four-month tours of duty.

[44] The 1975 Mason Review, a government white paper, outlined a new defence policy that removed the UK-based divisional-sized strategic reserve and also resulted in the restructure of the British Army of the Rhine (BAOR).

The approach intended to provide greater flexibility in tailoring forces to meet unforeseen events and allow for an overall reduction in the size of a division by 700 men.

It, like the Mason Review, aimed to balance the British military in line with the nation's financial resources and save manpower.

This framework sought to restructure the British military based on the new strategic situation, allow for further cost saving measures to be enacted, and to reduce the BAOR by half.

In the event of a major emergency, as part of agreements between the UK and Italy, the division could be reinforced by the 132nd Armored Brigade "Ariete".

During the 1990s, the division deployed troops to Angola, the Falkland Islands, Kosovo, Northern Ireland as part of Operation Banner, and Rwanda.

[44][61][62] Most notably, in December 1995, following the signing of the Dayton Agreement, the division was the first British formation deployed as part of the Implementation Force to serve as peacekeepers in Bosnia and Herzegovina and remained through 1996.

[62][64][65] Following the United States invasion of Afghanistan, in December 2001, the divisional headquarters was dispatched to Kabul as part of the International Security Assistance Force.

The task force was maintained until 2014, consisting of 1st Armoured Division units, when it was disbanded following the British withdrawal.

The British portion of this force was based around a reinforced brigade, which came from different parent formations and were rotated through several deployments.

[79] Further changes occurred following the 2015 Strategic Defence and Security Review, which resulted in Army 2020 Refine that was implemented in 2019.

[40] Norman Scarfe, the divisional historian for the period 1943-1945, argued against a continuation of the nickname beyond the First World War.

'Ironsides' is surely another not entirely justifiable reference to East Anglia, where Cromwell did his recruiting; and Iron, a symbol of strength and resolution of the 3rd Division in the Four Years' War, can also suggest inflexibility and cruelty, rust and robots.