Sergeant Henry Smallman enlisted in the 6th Dragoons at Dublin in June 1849, aged 18 years and was advanced to Corporal in August 1853. Embarked for the Crimea in the Europa in late May 1854, he was aboard her when she caught fire on the last day of the month when 123 miles west of the Scilly Isles. The two Mates and three Able Seamen at once deserted in one of the ship's boats, the rest of the crew following suit shortly afterwards. But for the good behaviour of the soldiers, many more might have lost their lives. As it was a Veterinary Surgeon, four Sergeants, 12 Other Ranks and two women were lost and Smallman and a few comrades were fortunate to be picked up by the Willoughby Moore.

Subsequently engaged in the Charge of the Heavy Brigade at Balaklava, in addition to the Battle of Inkermann and operations before Sebastopol (WO/100 refers), Smallman ran into trouble with higher authority in October 1855 and was sentenced to be reduced to the ranks, in addition to 42 days hard labour at Scutari. Back in England by late 1856, his Good Conduct Pay was restored and he was advanced to Corporal in February 1858.

Smallman was embarked for India at the end of the year and was posted to Kirkee soon after his arrival in Bombay. Here he gained advancement to Sergeant but does not appear to have seen any active service. In January 1860, he applied for his discharge by payment, a request that was granted.