Under the Duke of York, Clinton took part in the Flanders and Low Countries campaigns as a captain in the 1st Guards in 1793, winning promotion to Lieutenant Colonel the following year.

During 1812, Clinton served in the Mediterranean leading a division at Messina on the Italian island of Sicily, where he commanded a force of 12,000 British and Spanish troops.

[2] He commanded the 1st Division of the independent Army on the Tarragona, during the Peninsular War between 1812 and 1813, Clinton won distinction during the Battle of Castalla on 13 April 1813.

[3] Returning to his post as a member of Parliament, he would command a division consisting of around 5,000 soldiers during the First Miguelist War where he attempted to support Portuguese forces from December 1826 until April 1828.

Promoted a full general, Clinton resigned from Parliament serving as governor of Chelsea Hospital from 1842 until his death on 15 February 1846 on Cockenhatch, near Royston, Herts.