The Fonab of 1702 commanded the British troops sent to protect the interests of the colonists of Darien against the attacks of the Spaniards, and obtained a signal and decisive victory over a vastly more numerous force of the enemy at Toubocante.

Serving some time in Canada with that regiment, he changed into the 15th Hussars under the Earl of Cardigan; but in 1835 he left the army, and engaged himself in the management of his landed property at Monzie, his father having died in 1832.

About this time he was asked by the Conservative electors in Argyllshire to oppose the Liberal candidate; but though he was unsuccessful in the election of 1837, he so effectively advocated the Church's claims during his canvass, as to draw the attention and win the confidence of the non-intrusion leaders.

He entered Parliament as a Liberal Conservative, and so attracted the notice of Sir Robert Peel as to be offered by him a subordinate place under Government; but Mr Campbell felt it better to be free from party control, and declined the appointment.

At this period, in addition to his strong ecclesiastical convictions, he held Free Trade principles, and was a supporter of Vote by Ballot, both of which he insisted would prove truly Conservative measures.

After delivering several earnest speeches in Scotland on the impending crisis, he resumed for a time his place in Parliament, and wrote what has been called "a solemn letter to Sir Robert Peel, imploring him even at the eleventh hour to avert the breaking up of the Church, by instantaneous and satisfactory legislative interposition."

[5] On the very day of the Disruption, Mr Campbell wrote a circular to the Argyllshire constituency, intimating his resolution to resign his position as their representative, having felt constrained in conscience to differ widely from many of those who had originally elected him.

"[5] Hence he was much occupied for several years in labours connected with the Sustentation Fund, the General Assembly, the formation of the Evangelical Alliance, the Christian education of the people, the endowment of Popery, the sanctity of the Sabbath in reference to railway traffic, the destitution in the Highlands, and many other undertakings.

The presentation was made in Glasgow, on 14 April 1846, by Dr Thomas Brown, in presence of an enthusiastic audience ; while, on the 18 May following, the East of Scotland shewed their appreciation of his services by choosing him to lay the foundation of the John Knox Memorial Church, hard by the house of the Reformer in the city of Edinburgh.

[5] During the last ten years of his life, Mr Campbell laboured under insidious disease, which gradually unhinged his whole nervous system, and rendered him increasingly and painfully unlike his former self.