104th (New Brunswick) Regiment of Foot was a regiment of the British Army. The regiment had its origins in the New Brunswick Regiment of Fencible Infantry, a unit of fencibles raised for the defence of the colony of New Brunswick in 1803. Recruits were drawn from across British North America, Scotland, Ireland and existing British Army units. The regiment was formally entered into the establishment in 1806 with a strength of around 650 enlisted men but grew to almost 1,100 by 1808. In 1810 the regiment's officers requested that it join the British Army as a regiment of foot. This request was granted on 13 September 1810 and the unit was renamed the 104th (New Brunswick) Regiment of Foot.