William Smyth was born in Kent in 1781. He became an Assistant Surgeon with the 28th Regiment of Foot in 1804, at the age of 23. On the 22nd of August 1811, he became a Surgeon with the 45th Regiment of Foot.  

Smyth served in the Peninsula War with the 28th Foot (North Gloucestershire Regiment) from November 1811 to March 1812, and again from July 1813 to April 1814. During this time, he served at Busaco and Albuhera. He then served with the 45th Foot at Pyrenees, Nivelle, Nive, Orthez, and Toulouse. Smyth served with the 45th Foot during the 1st Burma War.  

Smyth was placed on Half Pay on the 14th of February 1821 and reinstated in 1822. He was married at Tunbridge Wells in 1826, and five months later was put on Half Pay on the 18th of January 1827 for good.  

He lived at Douglas on the Isle of Man and died at his son’s house at Market Bosworth on the 23rd of March 1855, aged 73.