Gomm joined his regiment in 1799 and was deployed to the Netherlands where he fought under the Duke of York and Albany at the Battle of Bergen in September 1799 and at the Battle of Alkmaar in October 1799 during the Anglo-Russian invasion of Holland. He also took part in Sir James Pulteney's expedition to Ferrol in Spain in August 1800 and, having been promoted to captain on 19 July 1803, he joined the Senior Division of the new Royal Military College at High Wycombe. He then served as assistant quartermaster-general under Earl Cathcart at the Battle of Copenhagen in August 1807.