He fought under his father during the siege and capture of Seringapatam in 1799 at the age of 17.

He later became a Lieutenant-General in the British Army and commanded the 73rd Regiment of Foot at the Battle of Waterloo in 1815.

He succeeded his father in 1829 to the barony and the family seat of Belmont House and Gardens near Faversham in Kent.

He had married Isabella Helana Handcock-Temple of Waterstown, Co. Westmeath on 28 May 1824.

William George Harris moved into Waterstown House after the wedding.