I'd like to add some further details to u/Malaquisto's survey if you wouldn't mind some additional context and a few extra leads.

Mal is correct that Jacobitism was a long-lived movement that adapted its contours according to the fortunes and goals of those under its aegis, and that while strong political and dynastic ideologies stood at the center of the 'cause', through its century of relevance it slowly adapted to cover a broad base of disaffections with the established Williamite and Georgian governments. But I believe it is important to stress the widely international context of Jacobitism and that many different 'strains' of Jacobite sentiment existed, many of which were inextricably tied to the intricate web of European political alliances, especially through the eighteenth century. Yet it wasn't only about politics; there were economic, social, and confessional aspects to Jacobitism, and it was expressed quite differently between each of the three kingdoms in the 'Atlantic archipelago'.

In England, the Anglican Church was effectively Episcopal and shared non-juring principles with a large portion of Scottish Jacobites in the north-east who in turn provided their armies with a primacy of support, despite the traditional Highland-centric slant to the memory of Jacobitism. The very core of Episcopal conviction, especially in Scotland, was thought to be incompatible with a Hanoverian succession, and this reinforces the fact that things were not drawn down the lines of Catholic versus Protestant.

And it wasn't just the clergy who were non-juring, but also the congregations over which they presided. As an ever-growing threat to the government, this led to some terrible depredations in both England and Scotland that saw registers made of 'unqualified' clergy and the locking up and destruction of meeting houses reminiscent of the anti-Catholic penal laws in England and Ireland from the previous decades. In Scotland, Episcopalians were treated markedly worse than Catholics, especially in the aftermath of the Forty-five rising.

While Mal focuses on the early years of Jacobitism in Ireland versus the Williamite regime shortly after the Revolution, some of its most formative years came after the Union of 1707 and was expressed under martial risings in 1715, 1719, and 1745. These all started and ended in Scotland, but English support was always going to be an absolute necessity. Tending to attract conservative aristocrats with 'country values' and flirted with by Tories but never officially committing, Jacobitism never materialized there in large enough numbers to influence the outcome. And because English Jacobites did not widely take up arms as the century wore on, the Stuarts increasingly came to lean on France for money, materiel, and martial support.

By the time that James Francis Edward was done with the idea of making another attempt himself, his son Charles Edward was representing Jacobitism in a very different light and to a considerably different populace than at the end of the previous century. After the Union, Scotland was the primary target for Stuart plans, but I disagree that half of Scotland was Jacobite. The high water mark of Jacobite martial participation was only around 20,000 in 1715, and a significant chunk of that was based on opposition to the Union in a kind of patriotic, proto-nationalistic melange. By 1745, time had passed and the economic benefits of the Union had been made more apparent to many, largely cutting into the zeitgeist of Jacobitism from the previous generation, and this is borne out by relatively weak national support after the last rising kicked off. Indeed, only about 1.14% (4.4% of adult males) of Scotland's population took active part in the Forty-five, and Jacobite command had a hell of a time recruiting and keeping troops in their ranks throughout the entire campaign.

I also disagree that Jacobitism was 'more of a Highlander thing', though we tend to remember it that way. Gaels were propagandized into being natural Jacobites, but only a quarter of the fifty primary clans were Catholic, they were often internally divided by allegiances and principles, and Jacobite sentiments tended to decline as chiefs drifted toward neutrality, influenced by more pragmatic concerns later in the eighteenth century. Highlanders might have been the traditional 'shock troops' of the later Jacobite armies, but Lowlanders from the north-eastern counties appear to have come out in greater numbers in 1745-6. Significant support likewise came from Lowland areas like Edinburgh and East Lothian.

I do not believe that Charles Edward ever represented himself as an enlightened liberal. Charles himself was razor-focused on restoring his father, and Jacobite proclamations explicitly promised tolerance to anyone who would join their effort to reclaim the throne. The Stuarts were always tracking the bigger picture, though, which was all three kingdoms or nothing, and they always represented the conservative, traditional principles versus what they viewed as the corrupted liberality and foreign progressiveness of the Whigs and their Hanoverian head of state. Jacobites did indeed have a coherent programme of government drawn up, but it never made it past a few provisional declarations on the local level, and the Jacobite logistical networks could not have supported it in the long term.

Finally, I'd like to address your question about why Jacobitism persisted beyond the active threat to the established government that it represented. The trappings of neo-Jacobitism that you identify through the Victorian era and even today hold very little in common with historical Jacobitism and really cannot be considered in the same breath. Modern Jacobites consider themselves to be regnal legitimists or Scottish nationalists, and from the historian's perspective have appropriated a lot of iconography and symbolism with little understanding behind what it meant during the long eighteenth century. As Mal suggested, the romance of the story long outlasted the movement, but the movement was, itself, extremely long-lived and one of the most dynamic and serious challenges to the British government in the early modern era.

If you would like to read a bit more about some particular aspects relating to your questions, I can recommend the following sources to you:

• Paul Monod, Jacobitism and the English People, 1688-1788 (Cambridge, 1989).

• Bruce Lenman, ‘The Scottish Episcopal Clergy and the Ideology of Jacobitism’ in Eveline Cruickshanks, ed., Ideology and Conspiracy: Aspects of Jacobitism, 1689-1759 (Edinburgh, 1982).

• Daniel Szechi, The Jacobites: Britain and Europe, 1688-1788 (2nd ed., Manchester, 2019).

• Allan Macinnes, Clanship, Commerce and the House of Stuart, 1603-1788 (East Linton, 1996).

• D. S. Layne, ‘Spines of the Thistle: The Popular Constituency of the Jacobite Rising in 1745-6’ (PhD thesis, University of St Andrews, 2016), pp. 58-62.

Hoping this has been useful!

With best wishes,
Dr Darren S. Layne
Creator and Curator, The Jacobite Database of 1745

Great question.

Okay so, yes King James was an absolutist divine right monarch. But that doesn't mean that Jacobitism was an absolutist divine right political movement! Jacobitism was a very broad tent, and at one time or another it reached out to pretty much everyone who had reason to be unhappy with the political status quo. And yes, that led to some pretty weird combinations sometimes.

The core of Jacobitism in England was among aristocrats and the landed gentry. These were groups that had skewed hard Royalist during the Civil War. They placed a very high value on legitimacy, and at the end of the day James was pretty clearly the legitimate King. The whole notion that he had abdicated was a pretty obvious fiction, whipped up to cover a coup backed by a foreign army. True, he had been a terrible King... but still, it was never going to sit well with the gentry.

James also got a lot of support from within the Church of England. Yes, it may seem weird that a Catholic ruler would find a lot of support from Protestant clerics and bishops. But remember, the King was the head of the Church of England, rather as the Pope was the head of the Catholic Church. There are a lot of Catholics today who sharply disagree with Pope Francis, and some who even consider him heretical. Now imagine that someone lands in Rome with an army, chases Francis out, and declares some other guy Pope. How are Catholics going to react? Well, some might say, great, Francis is gone and now we have a better Pope. But many will say, no matter how much we disliked Francis, we can never accept this usurper. Furthermore, some of the fiercest refusals would probably come from exactly the same stubborn traditionalists who decried Francis the loudest.

So in England, a huge chunk of the clergy and a number of the bishops refused to take the oaths affirming William and Mary as monarchs. These clerics were known as "nonjurors" and there were hundreds of them.

What I said about stubborn traditionalists? So, late in James' reign there was an event called the Trial of the Seven Bishops, which is exactly what it sounded like: James put seven bishops of the Church of England on trial for disobeying his instructions. The bishops stubbornly insisted on their rights and politely but firmly defied him; they were eventually acquitted. Well, just a couple of years later five of the Seven Bishops ended up as nonjurors. They disliked having a Catholic King and they disliked James and they refused to obey what they regarded as his unlawful order -- but they weren't going to swear loyalty to an usurper.

(A bit of trivia wrt nonjurors. First, if you ever saw the musical "Hamilton"? You might remember that in Act One, Hamilton debates and defeats a Loyalist named Samuel Seabury. Samuel Seabury ended up becoming an American bishop of the new American Episcopalian Church. But to become an Anglican or Episcopalian bishop, you must be consecrated by another bishop. And in England, all the consecration oaths involved swearing loyalty to the King of England... not really acceptable for a citizen of the new American republic. So Seabury went up to Scotland, where there were still some Scottish bishops who were nonjurors. And that is why the liturgy and ritual of American Episcopalian churches includes a mixture of both Church of England and Church of Scotland influences.)

Where was I... okay, so everyone who was unhappy under William and Mary at least flirted with Jacobitism. And a lot of people were unhappy under William and Mary. Remember, practically William's first act as King was to drag England and Scotland into an eight-year-long Continental war against France. This was expensive and -- after the first thrill of defying Louis XIV -- not particularly popular with much of the country. Also, William was Dutch, and many English (and some Scots) really did not like being ruled by a Dutchman. England had fought three wars against the Dutch within living memory, plus there were aggravations like commercial competition and the memory of the Amboyna Massacre.

King William spoke English fluently but with a heavy Dutch accent. He did not bother to conceal his preference for his country -- he was ostentatiously happy whenever he left London for the Netherlands -- nor his preference for his countrymen. It's understandable that he would appoint trusted Dutch friends to key positions, but it was deeply irritating to the aristocrats and senior gentry who craved those positions for themselves. Also, William was a brusque man who was often harsh and sometimes rude. He was intelligent, hard-working, and efficient, but he was not someone who suffered fools gladly or who had any patience for time-servers or gossips. And of course the long war with France meant that taxes went up and trade suffered. So, with one thing and another, soon there were a lot of people with buyers remorse about trading James for William.

One other small but interesting group of Jacobites: Protestant religious minorities. For complicated reasons beyond the scope of this comment, in 1687 James had extended religious tolerance to various minority Protestant groups. This was generally seen as (1) a stalking horse for extending religious tolerance to Catholics, and (2) an attempt to forge an alliance between these unconventional Protestants and the Catholic Church against the Church of England. Sort of a 17th century horseshoe theory, if you like. Anyway, while the effort failed, it left a lingering affection for James in some surprising places. Most famously, the Quaker leader William Penn was, if not an actual Jacobite, definitely Jacobite-adjacent -- friendly to a lot of Jacobites, and sympathetic to their ideas.

Finally, you mentioned two particular groups, the Irish and the Scots. In the case of the Catholic native Irish, it's very easy: they supported James because he was Catholic, full stop. They had their issues with him, sure. But they believed that a victory for William would be worse for them in pretty much every way. And of course, they were completely correct. William's reign saw the Battle of the Boyne, the flight of the Wild Geese, the near complete extinction of native Irish Catholics as a political power in Ireland, and the beginning of the Protestant Ascendancy that would last for the next 200 or so years.

The Scots... oh man, this gets complicated. Teal dear, late 17th century Scotland was a snake-pit of treachery, corruption, family feuds, vicious political rivalries, and conflicted loyalties, and that's before you bring the Scots Highland clans into the mix. So, nearly half of Scotland was Jacobite because the other half was Williamite. I know that sounds kind of simplistic but, really, that's pretty much how it was. The Scots Church was no help here, because it was undergoing a violent schism between Presbyterians and... you know what, never mind. Church of Scotland history is just insane. I mean, this is a church whose post-Reformation history includes stuff like "The First Secession", "The Second Secession", "The Disruption", and "The Killing Time". Let's just leave them out of this.

Anyway, later on -- under the Hanoverians, when Lowland Scotland began to seriously prosper after the Act of Union -- Jacobitism would become more of a Highlander thing. But by that time, 1720s and beyond, it was morphing into a nostalgic / romantic / anti-authoritarian movement based around resentment of the Crown and those pushy Lowlanders, not about any desire to restore Catholicism or absolutism.

Finally, as to ideology, Jacobite ideology morphed and evolved over time, so that by the 1740s Bonnie Prince Charlie was presenting himself as the enlightened liberal alternative to the corrupt and backwards regime of the aging George II. At all times, though, it was kind of a mess. There were certain core elements, like legitimism, that were always present. But it was mostly an ideology of opposition, not a coherent program for government. That made it easier for Jacobitism to survive -- and it survived a crazy long time; Jacobitism was a serious military threat for over 50 years. But it meant that from a modern perspective, it's often hard to make a coherent narrative about just exactly what they wanted.

I hope this helps!