He served in the Peninsular War, arriving in Portugal in 1809, as a Lieutenant of the 16th Light Dragoons Regiment, under the command of Lord Cambermere. He was present at Albergaria, Grijó and in the pursuit of the French Army under Marshall Soult on their flight to Salamonde.
At the battle of Talavera he commanded the united skirmishers of the 14th, 16th and 23rd Light Dragoons and of the 1st German Hussars of the 2nd Cavalry Brigade under the command of Brigadier General Stapleton Cotton.
In 1810 was promoted a Captain of the Portuguese Army by Marshall Beresford serving as Aide-de-Camp of General Fane commander of a Brigade attached to the Hill Division on the retreat to the Lines of Torres Vedras and operations thereafter.
As a Major, he then served as aide de camp of General Benjamin d’Urban, commander of the Portuguese Cavalry Brigade.
At the battle of Vitória he commanded the cavalry charge that ended French resistance, having attracted the attention of Lord Wellington.
At the end of the war, in 1815, Owen entered the service of the Portuguese Army as a Lieutenant Colonel of the 6th Chaves Dragoons Regiment.
But, by this time the 1820 Revolution had taken place and the Provisional Junta had dismissed Marshall Sir William Beresford and all British Officers in the Portuguese Army.
For his services during the Peninsular War he was made a Knight of the Order of the Tower and Sword and a Commander of the Order of St. Benedict of Avis. Awarded also the Army Gold Cross and the Peninsular Military General Service Medal with 4 clasps for Talavera, Albuera, Vittoria and Pyrenees and three Spanish medals.
In 1832, at the start of the Civil War he lived at Oporto then taken by the troops led by D. Pedro, duke of Braganza who immediately invited him the command the Cavalry as a General. Col. Owen refused being a British citizen and obeying the instructions from H.M. Government. But during the siege of Oporto by D. Miguel’s army he gave his collaboration to D. Pedro.
He published his memoirs of that period - The Civil War in Portugal: And the Siege of Oporto, London, E. Moxon, 1836, of which there was a Portuguese edition - O Cerco do Porto contado por uma Testemunha - O Coronel Owen, Porto 1915.
In 1856 he returned to Britain leaving behind his wife and children.
In his bookplate Colonel Hugh Owen bears pending from his arms the insignia of the Order of the Tower and Sword and its motto - «Valor e Lealdade». In the first and second quarters his other medals are shown.