His elder brother, John Griffiths of Erryd, was a medical practitioner and surgeon to Queen Charlotte's Household 1792–1818.
He was wounded in the general action on 6 February 1792, when the enemy's lines were stormed under the walls of Seringapatam and at the siege of that capital.
He served in Flanders with the army under the Duke of York, and was in the actions of 17/18 May, and at the storming of the village of Pontechin on 22 May, with the brigade under Major-General Henry Edward Fox, consisting of the 14th, 37th, and 53rd Regiments.
During the Napoleonic Wars, Griffiths was subsequently placed on the staff in Ireland and England, and received the brevet of colonel in 1810.
In the neighbouring Straits he commanded for nearly two years the British auxiliary troops in the fortress of Ceuta.