Archibald held the office of Master of the Household on 28 October 1529. He held the office of Master of the King's wine cellar on 28 March 1542. In 1543 the lands of of Muckart, Perthsire were bestowed on him for his services in the defence of the Church against heresies. He held the office of Justiciar of Bute in 1545. He fought in the Battle of Pinkie on 10 September 1547, where he commanded a body of Highlanders. He fought in the Siege of Haddington in 1548. After 1548 he was won over by English gold, and went over to the English side.
At an early period Argyll came under the influence of Knox, and he subscribed the first band of the Scottish reformers. On his way to Geneva in 1556 Knox made a stay with him at Castle Campbell, where he taught certain days. After the agreement of the barons, in December 1557, that the reformed preachers should teach in private houses till the government should allow them to preach in public, Argyll undertook the protection of John Douglas, a Carmelite friar, caused him to teach publicly in his house, and reformed many things according to his counsel. To induce Argyll to renounce the reformed faith, the Archbishop of St. Andrews sent him a long and insinuating letter, to which he wrote an answer replying particularly to every article. He died in August 1558, whereof, according to Knox, the 'Bischoppis war glaid; for they thought that thare great ennemye was takin out of the way.'
Source www.thepeerage.com from The Dictionary of National Biography, Oxford Univ. Press
http://onlinebooks.library.upenn.edu/webbin/metabook?id=dnb