Campbell, Lady Agnes (d. c.1595), lady of Kintyre and Dunyveg , was the daughter of Colin Campbell, 3rd earl of Argyll, and Jean, daughter of Alexander Gordon, 3rd earl of Huntley. Her marriage to James MacDonnell (qv), 6th lord of Dunyveg, in 1545, the year in which he was elected lord of the Isles, helped to secure MacDonnell allegiance to the Scottish crown. Although it was alleged that she was already married, she was always publicly acknowledged as James's wife. After the marriage James largely gave his attention to the MacDonnell interests in Co. Antrim; his involvement in the local politics of Ulster brought him into conflict with Shane O'Neill (qv) and culminated in his death in captivity shortly after he was fatally wounded at the battle of Glenflesk (April 1565).
The widowed Agnes commanded the loyalty of a large following among the Scots mercenaries who were increasingly attracted to Ireland by changes at home, and she deployed considerable influence in Ulster, which she devoted to furthering the interests of her children. In July 1569, on Rathlin Island, she married Shane O'Neill's successor as lord of Tyrone, Turlough Luineach O'Neill (qv), bringing with her a dowry of some thousands of redshanks. Turlough appears to have contemplated using these forces in an attack on the Pale, but it soon became clear that Lady Agnes's loyalty to the MacDonnells and her Campbell relations set bounds to her husband's freedom of action. Rumours of a possible divorce circulated shortly after the honeymoon, but Turlough seems to have settled into a subordinate role, accepting both Agnes's judgement and her superior diplomatic skills, which she used to maintain amicable relations with both the MacDonnells and the government. At her behest, in 1571 Turlough agreed an accord with the English government, and again in June 1575 she negotiated peace terms with the earl of Essex (qv).
The English saw her as a restraining influence on her husband. Sir Henry Sidney (qv), who said that she ruled Turlough completely, was deeply impressed, describing her in his Memoir as ‘a grave, wise, and well-spoken lady, both in Scots-English and French, and very well mannered’ and as ‘a well wisher to peace, and a reverent speaker of the queen's majesty’ (Memoir, 75–6). Nevertheless, Agnes's commitment to her sons' claim to lands in the Glens of Antrim meant that large numbers of redshanks continued to cross the North Channel. In January 1577 Sidney parleyed with Turlough and Agnes at Newry. In this instance Sidney reported that Agnes clearly feared that her brother-in-law, Sorley Boy MacDonnell (qv), was a threat to the establishment of her sons and forbade Turlough from meeting the lord deputy till he agreed to assist her in forwarding their claims, and, as she put it, making them ‘stark in Ulster’ (CSPI, 1574–85, 107).
In 1583 Agnes came under some suspicion of intriguing with the Scottish court, although she insisted that her sole reason for visiting Scotland was to secure the tenure of her eldest son Angus to his lands in the western Highlands and Isles. In November 1583 she swore fealty to Elizabeth on behalf of herself and Turlough, and in May 1586 an indenture was drawn up by which she and Angus received by English tenure the estates known as ‘Bissett's lands’ in the Glens of Antrim, long claimed by Sorley Boy. In 1588 Angus was in dispute with the earl of Argyle, and Agnes went to the Scottish court again to try to win favour for him. In the same year she had discussions with the lord deputy, Sir John Perrot (qv), about the restitution of lands leased by her husband to Hugh O'Neill (qv). The secretary of state, Sir Geoffrey Fenton (qv), who was also present at the meeting, was impressed with her negotiating skills, describing her as both eager and sharp. Turlough Luineach died in 1595, and there is no further record of Agnes.
Lady Agnes and James MacDonnell had three sons (Archibald, who died in 1569; Angus, who was one of the few chiefs to remain loyal to the queen during the O'Neill war; and Ranald) and two daughters (Fiona, known as Iníon Dubh (qv), who married Aodh O'Donnell (qv); and Catherine, who married Shane O'Neill). She had another son, Sir Art O'Neill, with Turlough Luineach.