The 27th Regiment served throughout the Napoleonic wars including Egypt where it formed part of Sir Ralph Abercromby's force that fought theBattle of Alexandria against the French in 1801, the 2nd Battalion formed part of the garrison of that city after its capture. The 1st Battalion served in the Calabrian campaign and fought at Battle of Maida on 4 July 1806. In this engagement the light company fought in James Kempt's brigade while the one grenadier and eight line companies belonged to Lowry Cole's brigade.
The 3rd Battalion disembarked in Lisbon in November 1808. It became part of Arthur Wellesley, 1st Duke of Wellington's army and fought at many of the key battles including Badajoz, Salamanca,Vitoria, the Pyrenees, Nivelle, Orthez, and Toulouse. The 3rd Battalion belonged to Cole's 4th Division throughout the war. At the Battle of Sorauren (Pyrenees), the 3rd/27th lost two officers and 41 men killed, nine officers and 195 men wounded, and seven men taken prisoner. At Toulouse, the unit lost two officers and 23 men killed, and five officers and 76 men wounded.
The 3rd Battalion went on to fight at the Battle of Waterloo as part of John Lambert's 10th Brigade in the 6th Division. At about 6:30 PM, the French captured the key strongpoint of La Haye Sainte farm. After this success, they brought up several cannon and took the Anglo-Allied lines under fire at extremely close range. At this period, the 698-strong battalion was deployed in square at the point where the Ohain road crossed the Charleroi to Brussels highway. At a range of 300 yards, the French artillery caused the unit enormous casualties within a short time. At day's end, the 3rd Battalion had lost 105 killed and 373 wounded, a total of 478 casualties. The unit was described as "lying dead in a square".
The 27th and all the other British Infantry units that fought at Waterloo are available through the website