He was the eldest son of George Clifford, esq., of Bobbing Court in Kent, by his wife Ursula, daughter of Roger Finch. He served in the army sent under Robert Devereux, 2nd Earl of Essex to the siege ofRouen in 1591, being then a captain. He and John Wotton especially distinguished themselves in rescuing from the enemy the dead body of the earl's brother, Walter Devereux, who had fallen into an ambush during a demonstration before Rouen. In the same year Clifford was knighted. He represented the borough of Pembroke in the parliament which met 19 February 1593. At the bachelors' commencement in 1595 the University of Cambridge conferred on him the degree of M.A. On the news being received of the siege of Calais by the Spanish, the Earl of Essex pushed to Dover; he wrote to Sir Anthony Shirley that he had sent Clifford to see whether he could ascertain the state of the town. Later in the same year Clifford accompanied the expedition against Cadiz, in the capacity of serjeant-major of the troops. He was one of the officers who formed the council. The declared value of his share of the plunder was £3,256. By letters patent dated 4 September 1597 he was appointed President of Connaught in Ireland, with the command and conduct of forty horsemen and a band of footmen. For some months previously he had acted as chief commissioner of the province, and constable of Athlone Castle. The Earl of Essex, having received a supply of a thousand men from England, prepared to march northward, and, to divide the forces of Hugh Ó Neill, 2nd Earl of Tyrone, he directed Clifford to penetrate from Connaught into Ulster to create a diversion. Clifford's force consisted of fifteen hundred foot and a hundred horse. In August 1599, on coming to the Curlew Mountains, near Boyle, County Roscommon the baggage and ammunition were halted under the protection of the horse, while the infantry attempted the passage. The Irish under Brian Óg O'Rourke had blockaded the passage and began their assault on Clifford's men. The Battle of Curlew Pass ensued and the English, having nearly exhausted their ammunition, were seized with a panic and took to flight. With the assistance of Hugh Roe O'Donnell's men, O'Rourke decisively defeated the English at Curlew Pass and Clifford was left mortally wounded after being struck through the body with a pike. O'Donnell ordered O'Rourke to cut off Clifford's head and send it to the besieged O'Connors of Sligo as a sign that no English aid was coming. Upon receiving the head, they surrendered. Clifford's body was honourably buried at Holy Trinity Abbey, Lough Key and his "tragic death….was much lamented" by the Irish lords, as the man had "never told them a falsehood". Clifford left in manuscript A brief Declaration relating to the Province of Connaught, how it stood in 1597.
Family
Clifford married Mary, daughter of Francis Southwell of Wymondham Hall, Norfolk, and widow successively of Thomas Sydney of Wighton and Nicholas Gorge. By her he had issue two sons, Henry and Conyers, and a daughter, Frances, who died young. His wife survived him, and married as her fourth husband, Sir Anthony St Leger, knight, Master of the Rolls in Ireland. She died in childbirth on 19 December 1603, aged thirty-seven, leaving a son, Anthony, and a daughter, also Frances, by St Leger; Frances outlived her mother by only a few days. Mary is buried in St. Patrick's Cathedral, Dublin.
