In 1854 he volunteered in the Turkish Army, received the rank of major, and, after visiting the Crimea, proceeded to Kars, where he arrived in March 1855. Under the command of Colonel Fenwick Williams, he gave important assistance in strengthening the fortifications. He distinguished himself in repelling the Russian assault on 29 September, crushing the Russian columns by his fire from Arab Tabia. His bravery won the admiration of the besiegers, and, on the surrender of Kars in November, Nikolay Muravyov-Karsky, the Russian commander, returned him his sword. On 9 November he was appointed captain unattached in the British Army; on 7 February 1856 he received the third class of the Turkish Order of the Medjidie; and on 10 May was nominated an honorary CB.