After entering Parliament in 1797, he served as Under-Secretary of State for Foreign Affairs from 1806 to 1807 in the Ministry of All the Talents headed by Lord Grenville.
[1] In 1795 Walpole went with the 13th Light Dragoons to the West Indies, and took a leading part in the suppression of an insurrection by Maroons in Jamaica.
The country was extremely difficult for regular troops, and two of the detachments sent against the Jamaican Maroons fell into ambushes, and their commanders (Colonels Sandford and William Fitch) were killed.
At the beginning of October Walpole was charged with the general conduct of the operations, and the governor – Lord Balcarres – gave him the local and temporary rank of major-general.
[3] However, the Maroons of Trelawny Town were unable to maintain their guerrilla campaign during the drought months, and when Walpole employed a scorched-earth policy, backed up by the importation of hunting dogs, on 22 December Walpole was able to persuade the Trelawny Maroon leader, Montague James, to come to terms.
Only a few of the insurgents came in, and in the middle of January Walpole moved against them with a strong column, accompanied by dogs which had been brought from Cuba.
They then surrendered, and were sent down to Montego Bay; and in March the assembly and the governor decided to ship them to Nova Scotia.
He declined a gift of five hundred guineas which the assembly voted for the purchase of a sword, and obtained leave to return to England.
[7] Walpole maintained contact with the Trelawny Maroons while they were in Nova Scotia, arguing in vain in parliament that they were unfairly treated by Balcarres.