3rd Mechanised Division ( United Kingdom ) The 3rd Mechanised Division , known at various times as the Iron Division , 3rd ( Iron ) Division or as Iron Sides ; is a regular army division of the British Army . It was created in 1809 by Arthur Wellesley , 1st Duke of Wellington , as part of the Anglo - Portuguese Army , for service in the Peninsular War , and was known as the Fighting 3rd under Sir Thomas Picton during the Napoleonic Wars . The division is also sometimes referred to as the Iron Division , a nickname earned during the bitter fighting of 1916 , during the First World War . The division ' s other battle honours include : the Battle of Waterloo , the Crimean War , the Second Boer War , the Battle of France ( 1940 ) and D - Day ( 1944 ) . It was commanded for a time , during the Second World War , by Bernard Montgomery . 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 British Mandate Palestine . During the Second World War , the insignia became the " pattern of three " — a black triangle trisected by an inverted red triangle . Napoleonic Wars . Peninsular War . The Division was part of the British forces that took part in the Peninsular War and fought in the Battle of Sabugal , Battle of Orthez , Siege of Badajoz ( 1812 ) , Battle of Salamanca , Battle of Nivelle , Battle of Fuentes de Oñoro , Battle of Vitoria , Battle of Bussaco and the Battle of the Pyrenees Peninsular War Formation . Battle of Vitoria example Commanding General : Lieutenant - General Sir Thomas Picton ( 7 , 500 ) 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 ) . The 3rd held their ground and pushed on with other divisions to capture the village of . Waterloo Campaign . The 3rd Division was also present at the Battle of Quatre Bras and the Battle of Waterloo . in the Waterloo campaign under the command of Lieutenant - General Sir Charles Alten K . C . B . ( Count Carl von Alten ) Battle of Waterloo formation . 5th Brigade . Major - General Sir Colin Halkett K . C . B . 2nd Brigade , King ' s German Legion . Brevet Colonel Baron Christian Freiherr von Ompteda 1st Hanoverian Brigade . Major - General Friedrich , Graf von Kielmansegge Artillery . Lieutenant Colonel John Samuel Williamson Crimean War Formation . The 3rd Division took part in the Crimean War and fought in the Battle of Alma and the Siege of Sevastopol ( 1854 – 1855 ) Second Boer War . During the Second Boer War ( 1899 - 1902 ) the division began under the command of General Gatacre but was subsequently partially absorbed into the Natal Field Force under the command of General Francis Clery . First World War . During the First World War it was a permanently established Regular Army division that was amongst the first to be sent to France at the outbreak of the war . It served on the Western Front for four years . During this time , it was nicknamed " The Iron Division " . Its first commander during the war , Major - General Hubert Hamilton , was killed by shellfire near Béthune in October 1914 . WWI Composition . During WWI 3rd Division ' s composition was as follows : The brigade moved to the 25th Division in October 1915 and was replaced by the 76th Brigade . The following battalions joined the brigade for periods in 1914 and 1915 . The following battalions joined the brigade for periods in 1915 and 1916 . The following battalions left the brigade for the 76th Brigade when it joined the division in October 1915 : Other battalions to serve with the brigade were : The brigade moved to the 28th Division for a brief period in early 1915 . The brigade joined the division from the 25th Division in October 1915 . After the end of the First World War , the division was stationed in southern England where it formed part of Southern Command . In 1937 , one of its brigades was commanded by Bernard Montgomery . He assumed command of the division shortly before Britain declared war on Germany . Second World War . The Division was part of the ill - fated British Expeditionary Force evacuated from Dunkirk early in the Second World War . Composition 1939 – 40 . From the outbreak of war until the Dunkirk evacuation the composition of 3rd Division was as follows : General Officer Commanding : Maj - Gen Bernard Montgomery 7th Brigade ( Guards ) 8th Infantry Brigade 9th Infantry Brigade Divisional Troops Composition 1940 – 44 . For over a year after Dunkirk the composition of 3rd Division remained largely unchanged ( except that the motorcycle battalion was converted into 3rd ( Royal Northumberland Fusiliers ) Reconnaissance Regiment ) . Then , in September 1941 , 7th Brigade ( Guards ) was transferred to the Guards Armoured Division , and the following November 37th Independent Infantry Brigade HQ joined 3rd Division and was renumbered 7th Brigade with the following composition : 7th Infantry Brigade The brigade anti - tank companies were disbanded during 1941 and 92nd ( Loyals ) Light Anti - Aircraft Regiment , Royal Artillery , joined the division in March 1942 . In June 1942 , 3rd Division was reorganised as a ' Mixed ' Division , with 33rd Tank Brigade replacing 7th Infantry Brigade : 33rd Tank Brigade By early 1943 , the experiment with ' mixed ' divisions was abandoned , and 3rd Division reverted to being an infantry formation , 33rd Tank Brigade being replaced by 185th Infantry Brigade from 79th Armoured Division : 185th Infantry Brigade Thus the division had attained the organisation with which it went into action on D - day . D - Day . 3rd Division was the first British formation to land at Sword Beach on D - Day . For the assault landing , 3rd Division was organised as a Division Group , with other formations temporarily under its command . These included 27th Armoured Brigade ( Sherman DD amphibious tanks ) and 22nd Dragoons ( Sherman Crab flail tanks ) , 1st Special Service Brigade and 41 ( Royal Marine ) Commando , 5th Royal Marine Independent Armoured Support Battery ( Centaur IV close support tanks ) , 77 and 79 Assault Squadrons of 5th Assault Regiment , Royal Engineers ( Churchill AVRE s ) , plus additional Royal Engineers , Royal Artillery and Royal Army Service Corps . The division ' s own artillery were all self - propelled ( field regiments : M7 Priest ; anti - tank regiment : M10 tank destroyer ) and the SP field guns and RM Centaurs were able to fire from their landing craft during the run - in to the beach . In addition , 3rd Division had 101 Beach Sub - Area HQ and Nos 5 and 6 Beach Groups under command for the assault phase : these included additional engineers , transport , pioneers , medical services and vehicle recovery sections . 3rd Division ' s brigades were organised as brigade groups for the assault , with 8 Bde Group making the first landing , followed by 185 Bde Group and 9 Bde Group in succession during the morning and early afternoon . After D - Day . After D - Day 3rd Division fought through the Battle of Normandy , the Netherlands and later the invasion of Germany . For the campaign in Normandy , the division was commanded by Major General Tom Rennie until 13 June 1944 ; Major General Lashmer Whistler , a highly popular commander , took command on 23 June 1944 . During the often intense fighting from Sword Beach to Bremen , the Division suffered 2 , 586 killed . Post Second World War . Postwar , the Division was reformed on 1 April 1951 , in the Suez Canal Zone , under the command of Sir Hugh Stockwell . The division became part of Middle East Land Forces . It consisted of three recently reraised brigades , the 32nd Guards , the 19th Infantry , and the 39th Infantry . It served in the UK for many years ; in 1968 it was part of the Army Strategic Command , comprising 5th , 19th , and 24th Brigades . It was an armoured division in the British Army of the Rhine from 1977 to 1991 . When its sub - units were Task Force Echo ( TFE ) and Task Force Foxtrot ( TFF ) , these changed around 1980 to 6 Armoured Brigade and 33rd Armoured Brigade . Current formation . The division was re - raised in the mid - 1990s after 3rd Armoured Division disbanded in BAOR . It providing the headquarters for Multi - National Division ( South - West ) in Bosnia - Herzegovina in 1995 / 1996 and again in 1998 . For a time it comprised 1st Mech Bde , 5th Airborne Brigade , and 19th Mechanised Brigade . On 1 September 1999 the Division was freed from its administrative and regional responsibilities and it became a deployable or " fly - away " division . As 3rd ( UK ) Mechanised Division it is now the only division at continual operational readiness in the United Kingdom ( the other at operational readiness being 1st ( UK ) Armoured Division in Germany ) . It is based at Picton Barracks , Bulford Camp , in Wiltshire and reports to the Commander Land Forces at Andover . Under the divisional command were four ready brigades , now three . 4th arrived from Germany while 19th disbanded . Future . Under Army 2020 , it will continue to be based at Bulford , and command the Reaction Force . Recent Commanders . Recent Commanders have been : < br > GOC 3rd Division GOC 3rd Armoured Division GOC 3rd ( UK ) Division GOC 3rd ( UK ) Mechanised Division