The Middlesex Regiment was one of the principal home counties based regiments with a long tradition. They inherited their nickname, the "Die-hards", from the 57th Regiment of Foot (West Middlesex), which later became the 1st Battalion, Middlesex Regiment.
The Middlesex Regiment's history is intertwined with the legacy of the 57th Regiment of Foot (West Middlesex), which contributed to their nickname "Die-hards" and ultimately led to the formation of the 1st Battalion, Middlesex Regiment.