THIS ANSWER AND ENSUING COMMENT CHAIN ARE PART OF A SUBREDDIT-WIDE APRIL FOOLS JOKE. THE REAL ANSWER IS HERE

I’m glad you asked this question, because it’s rare that people know enough about the Highland Army to a) realize it did suffer issues with desertion, particularly in the early part of 1746 leading up to Culloden and b) wonder why this was.

Like everything else associated with Jacobitism, this issue is usually buried in either aggressive Hanoverian propaganda or equally aggressive Scottish Romanticism. As usual, the truth lies somewhere in the middle.

To hear the Hanoverian side tell it, the highlanders were simply unsuited for warfare and wandered back home as soon as they were anywhere in the area. These were undisciplined men and boys who had never held anything more dangerous than a plowshare and had been scared by the rigours of war. Certainly understandable; people have deserted for worse. The Romanticists would have you believe the highlanders in fact did NOT desert at all—their absence was part of a diversionary tactic Lord George Murray had devised to disguise the army’s size in the lead up to battle. They were intended to take to the hills and convene near Baile Brèige in Haggis country in order to flank Cumberland’s army as it marched northward in pursuit. However, flash flooding in the area forced the Duke to redirect his men by way of Abhainn Sìthe, several miles further to the east, thereby evading Murray’s plans and ensuring the Highland Army was unable to regroup in time to stand at Culloden as a cohesive whole.

In fact, many men in the Highland Army did leave as they approached their home territories, though not due to desertion. Early spring is rutting season for many animals, chief among them the Haggis, an aggressive mountain animal related to the sheep common in the Northwest of Scotland. The Haggis was an important source of food for Highland families at this time, doubly so because of the ban on hunting red deer on Crown land.

As the Highland Army conveniently returned to Scotland at the end of January 1746, many men found it was close to Haggis rutting season and thus temporarily left the army to help with the hunt. Families without a hunter were at risk of starving until summer, when the heather harvest supplemented stocks, so there was a lot of pressure on these men to provide, regardless of their other responsibilities to fight for their King Over the Water.

Interestingly, this represents yet another bone of contention in the famous quarrel between Lord Murray and Prince Charles Edward Stuart. Murray being from Perth, in the Highlands (by the historical definition, not today’s), was well aware of Haggis season and the potential disruption it could cause to the campaign. His plan had been to consolidate Stuart power in Edinburgh over the winter until the end of Haggis season, then recruit heavily throughout the Highlands to secure additional regiments before going over the border. Charles, however, felt that the Highlanders were intensely loyal to him above all else and insisted that the army press its advantage into the lowlands. When they were forced to turn back from Carlisle, the Jacobite’s defeat was nearly certain: Haggis season was mere weeks away and the men were already planning their departure.

In vain, Murray tried to persuade them to stay, offering all manner of rewards and, when that failed, attempting to avoid Cumberland’s army as long as possible. The Duke, unfortunately, knew of his advantage and pushed relentlessly on, finally forcing the much-weakened Jacobite army to fight on the poor terrain of Culloden before the missing Highlanders could catch up, the hunting season having ended at the beginning of April.

Well then, now that April Fools has passed, time for debunking this one. The truth, I'm afraid, is rather more mundane; in fact, it's largely what I called Hanoverian propaganda in the original post. Remember that armies in the 1800s would be billeted in the homes of locals when they were in the army. Soldiers in the Highland Army (which note, was not comprised solely of actual highlanders) sometimes decided they'd rather billet at home, if they were in the area. Of course, this made mustering everyone rather more challenging, since the men didn't always let their officers know exactly where they'd be. There were also cases of actual desertion. This was a particular problem in the run up to Culloden, as the men were not given rations for three days prior (according to a very bitter letter from Murray to the Prince).

There was a long-standing feud between the Prince, who felt he should have last word by dint of who he was, and Lord George Murray, who felt he should have it by dint of actual stupidity. The feud came to an open split by the time the Jacobites crossed into England, as Murray did indeed feel it would be better to consolidate power in Edinburgh a while, but the Prince would have none of it. No form of animal hunting was involved with this spat.

Murray was indeed from the Perth area and Perth was part of the historic definition of the Highlands.

All campaign details are invented.

Finally, the big one, there's no such beast as a haggis. It's a national myth of Scotland, as well as a tasty dish made of sheep innards and spices (and honestly, don't knock it 'til you've tried it). All of that is invented.

And the linguistic Easter Eggs:

• Baile Brèige is basically "fake town" in Scottish Gaelic

• Abhainn Sìthe is "peace river"

• Agace haggenicus is a Latinized version of two possible etymologies of "Haggis"

• On the Haggis, Its Life, Habits and Habitat is an invented book, along with the "quotation" from it.

• Robert MacShabhdair is "Robert son of the Liar" again in Scottish Gaelic.

During which conflict?