[3] As Iain Ruadh's family was cultured and well-connected but no longer wealthy,[4] his father gave him a good education and procured him a commission as a Lieutenant in a Scots Greys which at that time was serving in Flanders.
In 1730, after being refused a commission in the Black Watch Regiment, Stewart resigned from the British Army and was subsequently employed as a covert agent between the House of Stuart government in exile at the Palazzo Muti in Rome and Lord Lovat in Scotland.
[6] After secretly visiting a friend from Strathspey at the British encampment on the night before,[7] Stewart fought in the French Royal Army under the command of Marshal Maurice de Saxe at the Battle of Fontenoy on 11 May 1745.
[8] He left his wife, Sarah Hall, and their daughter behind at Boulogne, and asked that Prince James Francis Edward Stuart see that his family be provided for should he fall in the coming rising.
[10] Iain Ruadh had previously fathered an illegitimate son named Charles Stewart, who fought for the Hanoverian army in Loudon's Highlanders during the Battle of Prestonpans.
"[13] According to an account attributed to fellow senior Jacobite Army officer Ewen MacPherson of Cluny, in September 1746, Prince Charles requested that Iain Ruadh Stùibhart be sent for.
For example, he compared the Jacobite rising to the events of the Book of Exodus, as an effort to set the British people free from enslavement to both Whig political ideology and the House of Hanover.
His two poems on Culloden are of great historical interest, revealing as they do the depth of bitterness that was felt towards the Prince's lieutenant general, Lord George Murray, by a section of the Jacobite leaders.