He was promoted to lieutenant the following year and served with his corps in Nova Scotia (1825–36), Ireland, Birmingham during the bread riots (1839), Jersey, and Malta (1841–43).
He arrived at Cawnpore early in November, and commanded, under Major-general Windham, a detachment of the Rifle Brigade at the Pandu Nudda.
Crossing the canal and moving along the outskirts of the western face of the town, Walpole successfully prevented the enemy's centre from supporting their right, which had been turned by the British 4th and 5th brigades.
On 18 December Walpole, with a detached corps of the army, consisting of the 6th brigade with the addition of a field battery, a troop of horse artillery, and a company of sappers, marched through the Doab, captured Etawa on 29 December, and on 3 January 1858 reached Bewar, where Brigadier-general Seaton's force, which had arrived already, came under his command.
He occupied the Dilkusha position on 4 March, and moved under Sir James Outram across the Gumti early on the morning of the 6th to take the enemy in reverse.
He surprised and captured the camp of Hashmat Ali Chaodri of Sandila, together with that of the mutinous 15th irregulars, taking their standards and two guns.
When Outram entered Lucknow on the 16th, Walpole was left to watch the iron and stone bridge, and repulsed a strong attack made upon his pickets.
On the 27th he was joined by the commander-in-chief, marched on Shahjahanpur, which, on the 30th, they found evacuated by the enemy, and pushed on without opposition, reaching Miranpur Katra on 3 May.
He was promoted to be major-general on 30 May 1862; brought home in 1864 to command the Chatham military district which he relinquished in 1866 and given the Colonelcy of the 65th (2nd Yorkshire, North Riding) Regiment of Foot in 1869.