The Royal Northumberland Fusiliers was one of England's premier county regiments and can trace its ancestry back to the year 1674, when England and the Netherlands signed the Treaty of Westminster. A provision of the agreement transferred the Dutch colony of New Amsterdam to England, which renamed it New York.
When first raised it was part of the Dutch Service and known as the Irish Regiment, or Viscount Clare's Regiment. Like most regiments, it was known until 1751 by the names of the colonels who successively commanded them.
The Regiment was transferred to the British Service in 1689. On 1 July 1751, when the system of naming regiments after their Colonels was dropped, it was designated the 5th Regiment of Foot.
On 1 August 1782 it became 5th (The Northumberland) Regiment of Foot. It fought in the 1811 and 1812 Sieges of Badajoz.
In 1836 it became a fusilier regiment, the 5th (Northumberland Fusiliers) Regiment of Foot. With the Cardwell reforms of 1881 and the general loss of numbering, it became the Northumberland Fusiliers. In 1935, the regiment was given the prefix "Royal".
In 1968, it became the 1st Battalion of the Royal Regiment of Fusiliers. The Royal Regiment of Fusiliers continues to wear some of the insignia of the four county regiments from which it was formed and to honour their traditions and carry their battle honours.