MacDonnell, Sorley Boy (c.1512–90), lord of the Route and constable of Dunluce castle, was sixth and youngest son of Alasdair Cahanagh MacDonnell, lord of Dunyveg and the Glens (Glynnes) of Antrim, and his wife Catherine, daughter of John MacIan MacDonnell, lord of Ardnamurchan. He was probably born at Dunanynie castle, just west of Ballycastle, the seat of MacDonnell power in Ulster in the early sixteenth century. In the 1530s and 1540s there was significant migration from the Western Isles into the Glens, and the MacDonnells set about extending their control westward into the Route and southward into northern Clandeboye.
After the death of their father (1538) Sorley took possession of Dunanynie castle and assisted his older brothers James (qv) and Colla (qv) in the execution of this enterprise. In 1550 he was captured and imprisoned in Dublin castle in unknown circumstances, apparently as a preliminary to the campaign by Sir James Croft (qv) in north-east Ulster. He was released in the following year in an exchange of prisoners after the collapse of the expedition. In November 1551, he joined James in an invasion of the O'Cahan lordship; shortly afterwards he and Colla attacked Carrickfergus, captured the chief constable and held him to ransom.
On Colla's death (1558), James MacDonnell appointed Sorley to succeed him as captain of the Route. Sorley's authority was resisted by the MacQuillans, and in 1559, after raising a force in Scotland, he made a series of attacks on them. The MacQuillans suffered a decisive defeat in July at Slieve-an-Aura (south of Ballycastle), and Sorley was able to re-establish MacDonnell control of the Route. In 1560 he followed James in seeking official recognition of his possessions. On the advice of the lord deputy, the earl of Sussex (qv), who saw the MacDonnells as allies in curbing the power of Shane O'Neill (qv), the queen responded favourably. Sorley agreed to join a league against O'Neill on condition that he received a letter of denization and a grant of the lands he held as deputy for his brother. An agreement was concluded on 20 January 1561 but no action followed, and in October 1562 James MacDonnell attributed responsibility for this to Sorley who commanded the MacDonnell forces in Ulster and had been obliged to make an agreement with Shane O'Neill for his own safety.
The government decided to abandon its policy and explore the alternative possibility of using O'Neill against the MacDonnells. In September 1563 a treaty was concluded with O'Neill that led to more satisfactory results. Sorley was wounded in a battle near Coleraine in September 1564 and captured with his brother James after a decisive battle at Glentaise near Ballycastle in May 1565. Shane's fortunes declined thereafter, and following his defeat by the O'Donnells at Farsetmore (May 1567) he sought the assistance of the MacDonnells, whose power had been greatly increased by the arrival of reinforcements from Scotland under the command of Sorley's brother Alasdair Oge. Although Sorley was still held as a bargaining counter, the conflict of interests proved irreconcilable, and after two days of negotiation at Cushendun the MacDonnells turned on Shane, stabbing him to death.
On his release in 1567 Sorley became the acknowledged leader of Clan Ian Mor, and looked for a crown grant to the Glens. When the government hesitated, he entered into a series of agreements with Irish chiefs in the area, most notably the new O'Neill chief, Turlough Luineach (qv), and Sir Brian MacFelim O'Neill (qv), lord of southern Clandeboye. His status within this group was firmly established by a visit to Scotland, from which he returned in November 1568 with a large fighting force and politically enhanced by the marriages of his sister-in-law Lady Agnes Campbell (qv) to Turlough and her daughter Fiona (qv) to the young Hugh O'Donnell (Aodh Ó Domhnaill) (qv) of Tyrconnell in July 1569.
For some years there was an unusual interval of peace in north-east Ulster, but it was broken in the early 1570s by the queen's authorisation of the colonising projects of Sir Thomas Smith (qv) and the earl of Essex (qv) in the Ards and Clandeboye. On the advice of Smith, who understood the need to conciliate the MacDonnells, Sorley was granted a patent of denization in April 1573. But the gesture was undermined some months later, when Essex received a grant that included the Glens, the Route, and Rathlin Island as well as Clandeboye. After initial overtures to Sorley, Essex chose to dispossess the Scots rather than the Irish, and in June 1575 marched north to engage Sorley, while Sir John Norris (qv) and Francis Drake went by sea to attack Sorley's base at Rathlin, where they massacred almost everyone on the island, among them members of Sorley's family who had been sent there for safekeeping.
Sorley retaliated on 6 September 1575 by swooping down on Carrickfergus, carrying away all the townsmen's cattle and defeating the pursuing garrison. On his return as deputy in the same month, Sir Henry Sidney (qv) hurried to Carrickfergus and negotiated a truce on terms that involved the removal of Essex's garrison from Rathlin, Sorley's agreement to pay the annual levy known as ‘composition’, and, it seems, a promise by Sidney to consider favourably Sorley's request for the recognition of his right to the Glens and the Route. In dealing with Sorley, Sidney was influenced by his uncertainty as to the loyalty of Turlough Luineach. Soon afterwards, however, an approach from Turlough led to an agreement that reduced the potential usefulness of the Scots and allowed the promise to be forgotten.
During the late 1570s and early 1580s Sorley continued to increase his influence in the area, aided by the marriage of one of his sons to Turlough's daughter and by the government's preoccupation with the Desmond rebellion. News of the arrival of a large force of Scots in Ulster in the late summer of 1584 raised fears of invasion and prompted a new lord deputy, Sir John Perrot (qv), to move against them in force. The raiders had left with their spoils before he arrived in Ulster in September, but he decided to take the opportunity to demonstrate his power. He laid siege to Dunluce castle, which quickly submitted, and reached agreements with a number of Irish lords before returning to Dublin, leaving garrisons behind him.
Sorley, who had stayed out of reach, went to Scotland for help and returned in the following January with reinforcements. Meeting with unexpectedly firm government resistance, he proposed a settlement on the terms agreed with Sidney ten years earlier. Perrot declined to listen to any terms, and Sorley withdrew once again in early spring, only to return once more on 2 August with a large Scottish force with which he recaptured Dunluce castle and steadily regained the initiative. His success inclined the English government to settle with him and, despite Perrot's reluctance, negotiations brought him to Dublin where he made a formal submission on 14 June 1586. He received a grant by knight service of the greater part of the Route, comprising the lands between the rivers Bush and Bann, together with Dunseverick, Loughgiel, and Ballymoney, and the constableship of Dunluce castle. Since the Glens from Larne to Ballycastle had already been granted to his nephew Angus, son of Lady Agnes Campbell, the arrangement gave the MacDonnells secure possession of the lands they had long contested.
That objective achieved, Sorley remained at peace with the government. He died at Dunanynie castle in late January or early February 1590, and was buried in the older vault in the abbey of Bunnamairge. His son Randal is said to have transferred his father's remains to the new vault in 1621. By his wife Mary (d. 1582), daughter of Con O'Neill (qv), 1st earl of Tyrone, Sorley had among other children: Sir James (qv), who succeeded him and died at Dunluce on 18 April 1601; Alexander, who was killed in a skirmish in 1586; Sir Randal (qv), who was created Viscount Dunluce and earl of Antrim; Donnell; Angus; and Ludar. His daughters were married respectively to the chief of the Macnaghtens in Scotland; MacQuillan of the Route; Cormac O'Neill, brother of the earl of Tyrone; Magennis, lord of Iveagh; and Shane MacBrian MacPhelim O'Neill of Clandeboye.