Sir Duncan Campbell, 2nd Baronet and 6th Lord of Auchinbreck was commander of Argyll's troops in Ireland in 1641 and taking of Dunluce Castle, County Antrim. He held the office of Governor of Rathlin Island. He married first Margaret Blair, who was born about 1575. She was the daughter of the Lord of Blair, and died without issue. He married second, Miss Maxwell, daughter to the Lord of Newark. They had issue:
a) Dugald, Third Baronet, born abt 1629 in Auchinbreck. He succeeded his father in 1645 and sat in Parliament for Argyllshire in 1649. He died unmarried about 1662 and was succeeded by his nephew, Sir Duncan, son of Archibald Campbell of Knockumilie.
b) Miss Campbell, b. 1627, md. Lord of Lechnel.
He married third, 1628, Dame Jean Coloquhoun, Lady Cathcart, of Luss, Scotland. Duncan and Jean had issue:
a) Archibald, born abt 1629, of Knockamillie, who married Margaret Campbell, daughter to Colin, Tutor of Calder by whom he had a son, Sir. Duncan.
*a1) Sir Duncan: 4th Baronet eldest son of Archibald of Knockemelie; Member of Parliament for Argyllshire, 1689–1698; m. 1679/80 dau. of 1st Earl of Balcarres; d. abt 1700.
b) James: born about 1630 of Knockumilie. He married Janet McLoed about 1650.
d) Alexander of Strondour, born about 1635 was married to Jean, eldest daughter to the Lord of Ottir by whom he had issue. He was murdered after the surrender of Carnassarie Castle in June 1685.
One prisoner who would receive no mercy was Duncan Campbell, Lord Auchinbreck, the functional commander of the covenanters that day. Auchinbreck had ravaged the lands of Alasdair Mac Colla's Irish cousins in Antrim as a commander in the Scottish army in Ireland. Also he had plotted to assassinate Alasdair when Alasdair tried to reconcile with the Scottish army following the defeat at Glen Maquin. Now Alasdair had Auchinbreck brought before him. Alasdair offered Auchinbreck two choices, to be made longer, that is hanged, or made shorter, that is decapitated. Auchinbreck reportedly replied, "da dhiu gun aon roghain," which could be roughly translated as two worst alternatives without one choice. At this point Alasdair swung his two handed sword, and took off the top of Auchinbreck's head above the ears like the top of a soft-boiled egg.