[1] His parents had intended for him to follow his father into the church, but Turner was determined to become a soldier, and in 1632 he travelled to Germany and enlisted in the service of Gustavus Adolphus, then embroiled in the Thirty Years' War, under the command of Sir James Lumsden.

[1] In 1654 he embarked on a risky mission to Fife to gauge the possibilities of a Royalist uprising, while in 1657 he went to Danzig to offer his services to John II Casimir, King of Poland under the Polish–Lithuanian Commonwealth, and then travelled to Denmark to fight in the ongoing conflict with Sweden.

He adopted the tactic of the French dragonnades and quartered his troops in the houses of Presbyterian families: although he was given the nickname "Bloody Bite-the-Sheep" by Covenanters,[3] and he added to an existing reputation for cruelty, it appears that he did not exceed his commission and did not go as far in enforcing Episcopacy as he was being urged by Archbishop James Sharp and others.

[1] While pro-Covenanter sources characterise Turner as mercilessly severe, commentators from the opposite camp observe that he would have witnessed atrocities committed by armed Covenanters (specifically at the Battle of Dunaverty) and would have therefore been disinclined to be lenient.

[4] Despite his claims of not going beyond his commission, his actions provoked the Pentland Rising in 1666: surprised and captured at Dumfries, he was (according to some sources) repeatedly on the point of being put to death, but later escaped when some of his guards ran away, and he struck a deal (which was honoured) with the others to negotiate their surrender.

[1] He was also reputed to be the author of a satirical poem, Mitchell's Ghost, which accused John Graham of Claverhouse of infidelity with the wife of Lord Advocate George Mackenzie of Rosehaugh.

Defoe described him as a "butcher [...] rather than a soldier":[5] Robert Wodrow characterised him as "bookish", while Gilbert Burnet (who knew him well in later life) said that "he was a learned man, but had been always in armies" and described him as "naturally fierce, but was mad when he was drunk, and that was very often".