Lieutenant-Colonel John Blackadder (14 September 1664 – 31 August 1729) was a Scottish soldier who served with the Cameronian Regiment during the late seventeenth and early eighteenth centuries.

The fifth son of dissenting minister John Blackadder, he was a devout Calvinist, and joined the Cameronians – a predominantly religious regiment – as a volunteer cadet when they were raised in 1689 to fight for King William III.

[4] Blackadder spent some time with his father during this period, from whom he received a basic classical education, and attended humanities classes at the University of Edinburgh in the 1680s.

[2] Blackadder had developed firm religious views, very much in the mould of his father, and in 1689, on learning that a regiment of soldiers was being raised from among the members of the Cameronian movement, a Presbyterian sect, he volunteered as a cadet.th He was quickly promoted to lieutenant, probably through his connections to the lieutenant-colonel, William Cleland, who he had known at the university.

[6] The regiment had been raised for service in the Jacobite rising of 1689, and was present at the final Battle of Dunkeld in August of that year; here, it fortified the town and held off a strong force of Highlanders.

He was court-martialled for this, but pardoned by the King the following May and restored to his position; it did not seem to affect his standing in the regiment significantly, as he was promoted to captain, commanding a company, in January 1693.

[11] The regiment remained in the Low Countries for some time, before moving to Perth; in 1702, following the outbreak of the War of the Spanish Succession, they returned to Europe as part of an army under Marlborough.

The battle was at first inconclusive, however, and Blackadder held his forces on the bridge throughout the day in the belief that the Hanoverian army had been routed and the city would shortly be besieged.