Fortescue, Sir Faithful (c. 1580–1666), royalist army officer and settler, was the second son of William Fortescue (d. 1604) of Buckland, Filleigh, Devon, and his second wife, Susannah Chichester, daughter of Sir John Chichester of Raleigh in Kent. About 1604–5, at a very young age, he went to Ireland to serve under his uncle Arthur Chichester (qv), who became lord deputy of Ireland in 1605. With such a powerful patron, he prospered, and in 1606 was made joint constable of Carrickfergus. At some time after 1606 he married Anne (d. 1634), daughter of Garret, Viscount Moore (qv). After being passed over in the plantation of Ulster, he received 2,000 acres of land in the plantation in Wexford in 1614. In November of the same year the influence of his aunt and his father-in-law secured for him the prestigious post of commander of the lord deputy's horse. By 1613 he had established his residence at the castle of Dromiskin, which was five miles outside Dundalk. He leased the castle from the archbishop of Armagh and went on to build up a considerable estate around it. He purchased the territory of Clanaghartie in Antrim from Rory Óg MacQuillan, which was confirmed to him by royal patent on 30 May 1618. He had sold most of this extensive territory by 1624. At around this time he bought land near Scarva in Down. In 1617 he was knighted in England by James I and in November 1624, through Chichester's influence, he was given command of a company raised in England to be stationed in Ireland. Following Chichester's death the next year he wrote a biography of him. In 1625 he was commissioner of the peace for Antrim and Louth. He was returned as MP for Charlemont in 1613, and for Armagh county in 1634 and 1640. However, in 1634 the citizens of Dundalk withstood government pressure and refused to elect him, returning two catholics instead.
In 1632 the newly appointed lord deputy of Ireland, Thomas Wentworth (qv), appointed Fortescue to raise and act as lieutenant of the lord deputy's troop of horse and a year later sent him to review the military stores and garrisons of Leinster. However, their relationship deteriorated steadily thereafter owing to disputes over the payment of the newly raised troop and to Wentworth's refusal to favour Fortescue with any further military appointments or to pay his arrears. Eventually, Wentworth assented to Fortescue's repeated entreaties that he be allowed to surrender command of his company of foot to his son, but Fortescue resented the grudging and tardy manner in which this favour was granted. On one occasion, Fortescue made an irreverent comment about Wentworth's relationship with a noble lady; this was probably Fortescue's sister-in-law Eleanor Loftus with whom Wentworth was rumoured to be having an affair. This remark was reported to the notoriously thin-skinned lord deputy who angrily demanded an explanation from Fortescue. Although Fortescue managed to placate Wentworth, this incident further heightened the tension between the two men. Nonetheless, in 1640 he was still deemed sufficiently trustworthy to be made a captain in the Irish army raised to fight the Scottish covenanters. During late 1640 – early 1641, as Wentworth was impeached by the English parliament and condemned to death, a disgruntled Fortescue probably assisted his former patron's enemies. This would explain Wentworth's decision in May 1641, while in the Tower of London awaiting execution, to order Fortescue's dismissal as lieutenant of his troop of horse. This dismissal outraged Fortescue and he refused to stand down until after Wentworth's execution. In January 1641 he petitioned that he be promoted to the rank of lieutenant colonel in the Irish army. Instead he was made governor of Drogheda in the autumn of 1641.
Following the outbreak of rebellion in Ireland in October 1641 Fortescue hurried to Drogheda, which by November was the only major town between the advancing rebels and Dublin. He found only sixty horse and three companies of foot there and a hostile disposition among the inhabitants. Despairing of the situation, he resigned his commission and travelled to England to raise forces to defeat the rebels. A witness of events in Drogheda gives Fortescue the benefit of the doubt: ‘although willing to hazard his life for us, [he] yet was loth to lose his reputation also’ (Barnard, 5). His two eldest sons were killed in the siege that followed and a third was to die in the English civil war. The English parliament commissioned him to raise a company of foot and a troop of horse, and made him a colonel in an expeditionary force which it intended to send to Ireland. In 1642 Fortescue had to relinquish his command of Carrickfergus (of which he had become sole constable) when it was occupied by the Scottish expeditionary force. While he waited in Bristol in August 1642 to set sail for Ireland the civil war broke out in England and he was forced to fight for parliament against the king. At the start of the battle of Edgehill on 23 October, having revealed his intentions to the royalists the night before, Fortescue suddenly led his troop across the battlefield to fight for the king. His defection threw the entire right wing of the parliamentarian army into chaos and had a major bearing on the ensuing battle. Shortly afterwards he was made commander of the tenth regiment of the royalist army.
Following the defeat of the royalists in the first civil war, Fortescue fled to Ireland and is recorded as being in Dublin in September 1646. In July 1647 when the lord lieutenant, the marquess of Ormond (qv), handed Dublin over to parliament, he made as one of his conditions that Fortescue should not be punished. Fortescue nevertheless took ship for the Isle of Man but, believing that he was safe, landed in Wales in November; he was arrested and imprisoned in Carnarvon castle, and then transferred to Denbigh castle in August 1648. Many in parliament had not forgotten Fortescue's actions at Edgehill and Ormond's efforts to secure his release came to nothing. He was probably released in late 1648 or early 1649 and was with Charles II at Stirling in April 1651. He was present at the battle of Worcester where Oliver Cromwell (qv) annihilated the Scottish royalist army, after which he fled to the continent. Following the restoration in 1660 he returned to England and spent most of the rest of his life at court. He was restored as constable of Carrickfergus in 1660, though he surrendered this position to his son in October 1661, at which time he was made a gentleman of the privy chamber. Charles also favoured him with a number of sinecures and grants. He died between 24 and 28 May 1666 at his house at Bowcombe on the Isle of Wight and was buried at Carisbrooke.
Fortescue's first wife, Anne Moore, with whom he had ten sons and six daughters, died 5 September 1634. By 1637 he had married Eleanor, daughter of Sir Marmaduke Whitechurch and widow of John Symonds. He left no will, so his eldest surviving son Sir Thomas had to purchase his father's estates from his eldest brother's widow.