On the morning of 27 July, Dundee learned Mackay's forces were entering the Pass of Killiecrankie, a track nearly 3 kilometres (1.9 mi) long with the River Garry on the left and steep hills on either side.
Sir Alexander McLean and 400 men were sent to skirmish with the advance guard, while Dundee assembled the rest of his troops on the lower slopes of Creag Eallich, north of the pass.
As they advanced into the pass, the government army had the Jacobites on the high ground above and the river behind, while the narrow track made advance or retreat equally hazardous.
Mackay halted, moved off the track and deployed his troops facing uphill in a long line only three men deep to maximise firepower.

Mackay's force included Balfour, Ramsay and Mackay's regiments of the Scots Brigade, along with the newly raised regiments of Kenmure and Leven, part of Hastings' regiment, and 100 cavalry.
As the most experienced, the Scots Brigade under Balfour and Lauder was placed on the left, which provided the best field of fire.

The Jacobites formed into columns and were in position by late afternoon but Dundee waited until sunset, just after 20:00 pm to begin his attack.
Balfour's front line fired three volleys, killing nearly 600 Highlanders but their fire was partly masked by a shallow terrace on the hillside, while the regiments to their right apparently fled without firing a shot.
Following their usual tactics, the Highlanders fired a single volley at 50 metres, dropped their muskets, and using axes and swords crashed into Mackay's centre.

Killiecrankie is the first recorded use by British troops of the plug bayonet, which increased firepower by eliminating pikemen.
It was 'plugged' into the musket barrel, preventing further reloading or firing, so fixing them was delayed until the last possible moment.
Inexperience in their use and the speed of the Highland charge left the government troops defenceless and many fled, abandoning Balfour, who was killed along with James Mackay, Hugh's younger brother.
On the morning of 27 July, Dundee learned Mackay's forces were entering the Pass of Killiecrankie, a track nearly 3 kilometres (1.9 mi) long with the River Garry on the left and steep hills on either side. Sir Alexander McLean and 400 men were sent to skirmish with the advance guard, while Dundee assembled the rest of his troops on the lower slopes of Creag Eallich, north of the pass. As they advanced into the pass, the government army had the Jacobites on the high ground above and the river behind, while the narrow track made advance or retreat equally hazardous. Mackay halted, moved off the track and deployed his troops facing uphill in a long line only three men deep to maximise firepower.
Mackay's force included Balfour, Ramsay and Mackay's regiments of the Scots Brigade, along with the newly raised regiments of Kenmure and Leven, part of Hastings' regiment, and 100 cavalry. As the most experienced, the Scots Brigade under Balfour and Lauder was placed on the left, which provided the best field of fire.
The Jacobites formed into columns and were in position by late afternoon but Dundee waited until sunset, just after 20:00 pm to begin his attack. Balfour's front line fired three volleys, killing nearly 600 Highlanders but their fire was partly masked by a shallow terrace on the hillside, while the regiments to their right apparently fled without firing a shot. Following their usual tactics, the Highlanders fired a single volley at 50 metres, dropped their muskets, and using axes and swords crashed into Mackay's centre.
Killiecrankie is the first recorded use by British troops of the plug bayonet, which increased firepower by eliminating pikemen. It was 'plugged' into the musket barrel, preventing further reloading or firing, so fixing them was delayed until the last possible moment. Inexperience in their use and the speed of the Highland charge left the government troops defenceless and many fled, abandoning Balfour, who was killed along with James Mackay, Hugh's younger brother.
Battle of Killiecrankie