Killiecrankie is the first recorded use of the plug bayonet by British troops in battle; this increased firepower by eliminating the need for pikemen but required training and confidence in its use. The bayonet fitted into the barrel of the musket (hence 'plug'), preventing further reloading or firing and so fixing them was delayed until the last possible moment. Inexperience and the speed of the Jacobite charge meant Mackay's troops were effectively defenceless and the battle lasted under 30 minutes.