Immediately after succeeding as Earl of Argyll and to the offices of his father, in October 1529, he was put in command of an expedition to quell an insurrection in the southern Scottish Isles.
The voluntary submission of the main chiefs resulted; and Alexander MacDonald of Dunnyveg, a prime mover in the insurrection, was able to convince King James V of Scotland that he was personally well disposed to the government.
Archibald was therefore summoned before the King to give an account of the duties and rental of the Isles, received by him; and, as the result of the inquiry, he was committed for a time to prison.
After the arrest of Beaton, on 20 January 1543, Archibald retired to his own lands to muster a force in order to maintain the struggle against James Hamilton, Earl of Arran, who had been chosen governor.
On being summoned by the governor to disperse, they did not resist; but when it became known that King Henry VIII of England had succeeded in arranging a treaty of marriage between the young queen Mary and his son, Prince Edward Tudor, the Earls of Argyll, Huntly, Bothwell, and Lennox marched from Stirling with a force of ten thousand men, and compelled the governor to surrender to their charge, the infant Queen, with whom they returned to Stirling.
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, Archibald took on the protection of John Douglas, a Carmelite friar.
To induce Archibald to renounce the reformed faith, John Hamilton, Archbishop of St. Andrews, sent him a long letter, to which he wrote a detailed answer.