Its first action came in Ireland at the Battle of the Boyne in July 1690[4] and the siege of Limerick in August 1691 when it fought for William III against the Irish Army of the deposed James II.

[2] The 11th Regiment spent the early years of the French Revolutionary Wars serving as detachments in the Mediterranean with the Royal Navy.

[ii] The 1st Battalion, Devonshire Regiment was a Regular Army unit and, after absorbing some 500 reservists, departed for France, landing at Le Havre on 21 August 1914, just 17 days since Britain's entry into the war, as part of the British Expeditionary Force (BEF).

[38] The battalion served on the Western Front throughout the war, seeing action first during the Battle of La Bassée in October where they helped in the capture of Givenchy Ridge, followed by the First Battle of Ypres, where the battalion, in common with most of the rest of the British Regular Army, sustained very heavy casualties.

The battalion then took part in the Winter operations 1914–1915, occupying trenches in deep mud and snow before, in April 1915, suffering 200 casualties from shelling and German counterattacks after holding Hill 60 after its capture a few days before.

[39] The 2nd Battalion, assigned to the 23rd Brigade, 8th Division,[38] was another Regular Army unit, that was awarded the French Croix de Guerre for holding up the massive final German advance of the war at the Bois des Buttes on 27 May 1918, the first day of the Third Battle of the Aisne.

[42] The 1/4th, 1/5th (Prince of Wales's) and 1/6th Battalions of the Devonshire Regiment, all First Line Territorial Force (TF) units, were mobilised upon the outbreak of war, serving together in the Devon and Cornwall Brigade of the Wessex Division, and were sent to India.

[43] The 9th (Service) Battalion[iii] was one of the few British units to reach its initial objectives on the first day of the Battle of the Somme, albeit at the cost of 463 dead or wounded of the 775 men who went 'over the top', with only one officer remaining unwounded.

[44] The 8th (Service) Battalion, part of 20th Brigade reserve, was committed within 3 hours of the beginning of the attack and suffered 639 casualties on the first day.

[43] The experience of an 18-year-old volunteer joining the 35th Training Reserve Battalion, part of the Devon Regiment, in 1918, is provided by A S Bullock.

After Italy the brigade was withdrawn to Sicily and then the United Kingdom where it became permanently part of the veteran 50th (Northumbrian) Infantry Division and trained with them in preparation for the Allied invasion of Normandy.

On D-Day, 6 June 1944, it was intended that the battalion, commanded by Lieutenant Colonel Cosmo Nevill, should land at Le Hamel, on Gold Beach, behind the 1st Hampshires.

However, in December 1944, the 50th Division was disbanded, due to a severe shortage of infantrymen in the British Army at the time, and the battalion was transferred to the 131st (Lorried) Infantry Brigade, part of the 7th Armoured Division, The Desert Rats, and remained with them for the rest of the war, participating in Operation Blackcock in January 1945 followed by Operation Plunder where they crossed the River Rhine.

However, none of these units, save the 4th Battalion, saw active service outside of the United Kingdom and were used mainly for home defence, training or supplying the other battalions of the regiment with infantry replacements and served with many different brigades and divisions such as the 80th Infantry (Reserve) Division.

The battalion, along the rest of 6th Airborne, was withdrawn to England in early September where they received new replacements, equipment and continued training.

The battalion crossed the River Rhine in Operation Varsity in March 1945 alongside the U.S. 17th Airborne Division.