The backstory was labyrinthine even by Civil War standards. Scotland's Covenanter-dominated Parliament had sent its best army south to fight for the English Parliamentarians, leaving the home front defended by militia and second-line troops. Charles I designated James Graham, Marquis of Montrose -- a former Covenanter who had changed sides -- as Captain-General in Scotland. But Montrose needed soldiers. The answer came from Ireland: 2,000 professional troops under Alasdair Mac Colla, sent by Confederate Ireland at the instigation of the Earl of Antrim. Mac Colla landed on the west coast at Ardnamurchan in July 1644, gathered Keppoch MacDonalds and pressed Badenoch men into service, then met Montrose at Blair Atholl in late August. A small regiment of Athollmen raised by Patrick Graham of Inchbrackie completed the force.

From Blair Atholl, Montrose marched southeast toward Perth. The Covenanter government scrambled to assemble a defence, issuing call-up orders only four days before the battle. The result was an army heavy on untrained militia under Lord Elcho and the Earl of Tullibardine, with the only veteran officer being Sir James Scott of Rossie on the cavalry left. Their battle cry was said to have been "Jesus and no quarter!" -- a grim irony, given how the day would end. Some Perthshire levies called up by the government -- men from Clan Stewart, Clan Robertson, and Clan Graham -- took one look at the situation and deserted to Montrose instead.

The armies met on flat ground at Tippermuir, three miles outside Perth. Montrose stretched his line thin -- only three ranks deep by one account -- to outflank Elcho's front. Mac Colla's experienced Irish troops held the centre. When Tullibardine sent forward skirmishers to probe the Irish position, they were driven back in confusion. Montrose ordered the charge. The clash was brutal and brief. Mac Colla's veterans smashed into the untrained militia, whose front ranks broke almost immediately. On the right, Montrose personally led his Athollmen into Scott of Rossie's cavalry, pushing them back into the retreating infantry. The rout was total. As was grimly common in the era, most casualties occurred after the battle ended. Fleeing Covenanters were cut down all the way back to Perth. One account claimed a man could walk from Tippermuir to the city walls on the bodies of the slain.

Perth surrendered that evening and was sacked for two days, with Royalist troops stealing cloth worth 1,300 pounds from local merchants. But Montrose could not hold the city -- a stronger Covenanter force under the Marquess of Argyll was approaching from the west, and he needed recruits from Angus. He vacated Perth on 4 September. The battle's aftermath was also darkened by betrayal: Lord Kilpont, one of the Perthshire nobles who had defected to Montrose, was murdered shortly after by fellow Royalist James Stewart of Ardvorlich in a personal quarrel. Stewart escaped and later joined the Covenanters. Tippermuir revived the Royalist cause in Scotland and launched a campaign of extraordinary victories -- Montrose would rout government troops again at Aberdeen later that month. The battlefield is now protected by Historic Environment Scotland, its flat moorland still marking the ground where Montrose's improbable war began.