Sackville’s father, first cousin of Thomas Sackville† (later lord treasurer and 1st earl of Dorset), was probably returned for East Grinstead in 1563 at his powerful kinsman’s nomination.
In 1625 the 4th earl of Dorset recommended Sackville, presumably on leave, to the Rye corporation for election to the first Caroline Parliament.
Re-elected in 1626, Sackville received two committee appointments, one to consider the bill against adultery and fornication (4 Mar.) and, ten days later, another to draft legislation for the finding of arms and horses. He again made no recorded speeches, and probably returned to his regiment for the campaigning season. He was absent at the call of the House on 2 June.
In the following year Sackville retired from the army to marry the daughter of one of Buckingham’s bitterest critics, Sir William Walter, who disapproved of the match.
Sackville obtained a knighthood in April 1628 and the following year was involved in a project for the erection of a lighthouse on Goodwin Sands.
At the outbreak of the Civil War, Sackville, by now described as Dorset’s housekeeper, was charged with collecting arms and money for the king, for which he was imprisoned in the Fleet. No doubt he was a royalist sympathizer, like his cousin; but no delinquency could be proved against him and he never compounded.
