Hugh Cumming was commissioned Cornet in the 3rd Dragoon Guards on 30 July 1807, and promoted to Lieutenant on 2 November 1809. He served in the Peninsula from April 1809 until November 1810, including the battle of Talavera on 27/28 July 1809. He resigned his commission in December 1810.
The 3rd Dragoon Guards landed at Lisbon on 26th/27th April 1809 as part of Fane’s cavalry brigade. On 4 May they marched north to join Wellington’s army and took part at the battle of Talavera on 27th/28th July. On the 28th the 3rd Dragoon Guards and 4th Light Dragoons, having moved into the plain to the left, advanced to charge a column of the enemy’s infantry, but the attack was countermanded, and the two regiments, after supporting the charge of Major-General Anson’s brigade, were ordered to resume their former position.