Philip Sidney, Viscount Lisle, 3rd Earl of Leicester, 1619-98
Nobleman appointed lord-lieutenant of Ireland by Parliament, he actively supported the Commonwealth and Protectorate régimes but was pardoned at the Restoration.
Born in London in January 1619, Philip Sidney was the eldest son of Robert Sidney, second Earl of Leicester (1595-1677), and his wife Dorothy (c.1598-1659), daughter of Henry Percy, ninth Earl of Northumberland. When his father succeeded to the earldom of Leicester in 1626, Philip took the courtesy title Viscount Lisle. He attended Christ Church College, Oxford, then accompanied his father on diplomatic missions to Denmark and France. However, the Earl quarrelled with Lisle and favoured his second son, the republican theorist Algernon Sidney.
Lisle served in the Second Bishops' War as commander of a company of cuirassiers that formed the bodyguard of his uncle Algernon Percy, tenth Earl of Northumberland. Under Northumberland's patronage, Lisle represented Yarmouth on the Isle of Wight in both the Short Parliament of April 1640 and the subsequent Long Parliament.
In June 1641, the Earl of Leicester was appointed lord-lieutenant of Ireland in place of the Earl of Strafford. On the outbreak of the Confederate War, Lisle went to Ireland as commander of a cavalry regiment and rose to the rank of lieutenant-general of horse under the Marquis of Ormond. Lisle's sympathy for the Parliamentarian cause brought him into conflict with Ormond. He returned to England when Ormond began negotiations for the Cessation of Arms in 1643. Lisle married Lady Catherine Cecil, daughter of the Earl of Salisbury in May 1645.

Early in 1646, Parliament attempted to assert its authority in Ireland by appointing Lisle lord-lieutenant. However, It was a year before he took up the appointment. When he finally arrived in Ireland, Lisle quarrelled with Lord Inchiquin, who objected to the appointment and to Lisle's deference to Inchiquin's rival Lord Broghill. Lisle's commission expired in April 1647 and was not renewed.
Lisle was named as a commissioner on the High Court of Justice for the trial of King Charles I but took no part in the proceedings. However, he was a firm supporter of the Commonwealth and a regular member of the Council of State, sitting briefly as president in 1652. He was a moderate member of the Nominated Assembly in 1653 and supported the establishment of Cromwell's Protectorate, during which he continued to sit as a member of the Council of State. Lisle played a prominent role in Cromwell's second installation as Lord Protector in June 1657 and was a member of Cromwell's controversial Upper House in 1658. After Oliver's death in September 1658, Lisle supported Richard Cromwell as his successor.
After the Restoration in 1660, Lisle obtained a pardon for his activities during the Commonwealth and Protectorate then retired from public life. He was involved in a bitter argument with his father, and disputes with his brothers Algernon and Henry over the inheritance continued after he succeeded as third Earl of Leicester in 1677. He died in London in March 1698 and was succeeded as fourth Earl of Leicester by his son Robert Sidney.
Sources:
C.H. Firth, revised by Sean Kelsey, Philip Sidney, third earl of Leicester, Oxford DNB, 2004