Campbell was one of the most important figures in the Scottish-Ulster
political scene of the late 1500's. Her father was the 4th earl
of Argyle and her brother became the 5th, she was married to James
MacDonald of the Isles (d1565). In 1569 she married Turlough Luineach
O'Neill (c1530-1595) chief of the O'Neills.
She was regarded as a shrewd
diplomat, and was largely responsible for maintaining the power
of the O'Neill's, she was a key figure in the supply of Scottish
mercenaries deployed in Ulster and Connacht, she held immense influence
in Ireland and had it within her power to destroy or advance several
Irish Lords. In Scotland she was responsible for brokering truces
between the Campbell's and Macdonald's. There is no reference to
her after 1590 and it is assumed she died around this period.