The Division is made up 1 Mechanized Brigade (Tidworth), 4 Mechanized Brigade (Catterick), 12 Mechanized Brigade (Bulford) and 19 Light Brigade (Lisburn).

The Division can trace its history back to 1809 in Spain when in the early years of the Peninsular War the future Duke of Wellington decided to adopt, for the first time in the British Army, a permanent divisional structure to help him combat the French. The Division's first General Officer Commanding (GOC) was Major General Thomas Picton, a Welshman, who moulded the division in his own image resolute, tough, slightly eccentric and full of fighting spirit. The Division was known as 'The Fighting Division' and remained part of the Army structure throughout the 19th Century, fighting against the Russians in the Crimean War (1854-6) and against the Boers of South Africa in the Boer War (1899-1900).

The 20th Century saw the Division fight with distinction in the First and Second World Wars. In the First World War the Division was present at Mons (1914), Ypres (1915), the Somme (1916), Arras (1917) and finally part of the occupation force of the Rhineland (1918-9) earning the nickname 'Iron Division'. In the Second World War the Division had two distinct phases. Firstly it was part of the British Expeditionary Force to France to stem the German advance, but having fought hard yet ultimately unsuccessfully, it was evacuated from Dunkirk. The second saw it lead the assault on Sword Beach on D-Day and fight as part of 21st Army Group across northern Europe and into Germany in 1945.

In the post war years the Division has had many roles, from being the UK's Strategic Reserve, an Armoured Division based in Germany during the 1980s and to today's 3rd (United Kingdom) Division based in Wiltshire.

The last 20 years has seen the Division deploy to Bosnia and Kosovo in the 1990s and as a headquarters to Kabul, Afghanistan in 2001 and Iraq in 2003, 2006 and 2008.

The headquarters has force generated and prepared 12 Mechanized, 52 Infantry, 19 and 11 Light Brigades for operations in Helmand Province, Afghanistan and has recently taken command of 4 Mechanized Brigade on their return from Operation HERRICK 13.