The Regiment was raised in Ireland as a response to the Napoleonic crisis in 1793. This war took them around the globe, fighting through Europe, Egypt, South America, West Indies and Canada. In 1809 both Battlaions of the Regiment went to Portugal and took part in the Peninsular War. While the Regiment was serving in Portugal and Spain The Regiment took part in many battles and light engagements throughout their time of service, including the defence of Cadiz, the Battle of Talavera - where the regiment's casualties mounted up to 40%-, The Battle of Vitoria and the Battle of Barrosa where it gained a great honour.
This great honour was the envy of all other British Regiments in the Peninsular War. After a attack from the the 2nd Kings Legion Hussars the 8th regiment de Ligne started to retreat to the remainder of the French force, however the 87th Royal Irish Fusiliers gave chase and a melee accrued after a near devastating volley from the Fusiliers. During this engagement a young officer Ensign Edward Keogh spotted the eagle and gathered a few men to come with him, fighting through the line the small handful of British Troops made their way to where the eagle was being defended. Keogh ordering the capture of the Eagle charged forward slaying any French man which got in the way of his prize, he came face to face with the French officer carrying the eagle and as he grasped the staff, he was shot through the heart and died. He was then followed by Sergeant Patrick Masterson who killed the French solider responsible and grabbed the eagle from the French ensign who carried it, reputedly with the cry "By Jaysus, boys, I have the Cuckoo!". This made the 87th Royal Irish Fusiliers the first ever British Regiment to capture a French Imperial Eagle!