Thing is, without the first crusades, much of the man power and monies lost by the inept Byzantine involvements in the crusades would not have been spent. Leaving the men + monies at home.
Concessions to allow the venetians freedom of trade would never be needed. Further helping the dying nation.
Who would Saladin be without the Enemy? Without the need to retake anything?
Hi,
If Saladin was around, why not Saladin? The Enemy was there: Muslims had been trying to take Constantinople for 500 years before him. Not retake, but take. If not him, I'd make up someone else. No biggie, but it's going to be someone.
There is a general problem with alternate history: Once small changes are introduced, there is no reason to assume that anyone born in the next generation corresponds to real history.
If there are magi in Normandy, no William the Conqueror. Verditii in Italy? Different popes. Jerbiton in Constantinople? No Saladin.
Everyone likes inserting real historical figures into their alternate history, though, so I'll join the fun.
Anyway,
Ken
This is not a challenge to your reasoning, but a simple question: why do you put Bjornaer and Ex Misc with the Diedne? Canonically (and, fair enough, we are decidedly non-canon here) Ex Misc was principally anti-Diedne during the Schism, since many of the British/Irish traditions held a long-standing grudge against them. It was a feature of previous editions to consider Ex Misc to be nature-loving pagans and basically Diedne in disguise, but the 5e form of the house is quite different. Of the traditions we know about in the House, three are specifically connected to a Divine religion (Sahir, Karaites, Donatores), one is a pacifist (Pharmacopoeians), one is a strong supporter of the Order (Pralicians), and many of the others are interested only in their magics. Of those traditions named, only the Witches of Thessaly, the Damadh Duidas, and maybe the Cult of Orpheus are involved in paganism specifically. (Indeed, prior to the formation of Ex Misc, it is stated that hedge wizards were recruited into House Diedne; presumably specifically if it was a pagan tradition. Does this make Diedne a Societas? Possibly.)
With respect to the Bjornaer, they have an ancestor cult, but this explicitly does not interfere with religious beliefs. As mentioned in HoH:MC, many Bjornaer integrate their cultic teachings in a religious framework - they do not deny the pre-eminence of the Divine, and while they might be considered by the church to hold heretical beliefs at worst, at best they are simply non-standard Christians. One of the members of the Bjornaer Council - the head of Clan Sirnas - is a committed Christian.
I'm not sure therefore that it is a given that these two houses would join with Diedne. I think it is likely that elements of both houses would join, but not necessarily a sizeable fraction. I think portions of other houses might well join with Diedne if it became a religious divide of Pagan vs Christian. The Titanoi of Tytalus, subcults of Merinita, the neo-Mercurians of Mercere, the Mithraic cultists (mainly Flambeau), and several other mystery cults might well side with the Diedne to avoid persecution by 'crusader' magi.
Cheers,
Mark
Tremere clearly IF they retain their grudges yes(and in an alternate where they are close to destruction for meddling with the code, the end result could just as well go the way of "we must distance ourselves from the mistakes of past that almost ruined us" as "we must destroy those bastards!".
Neither Flambeau nor Jerbiton would be so monolithic and certain though.
I doubt this assumption. Just as the moslems are not innocent victims of the crusades, they are also not the only potential source of "enlightement" or whatever you want to call it.
And the "no-crusades" is also unlikely. Even if they would likely start and happen differently.
Tremere would be closer.
Been very interesting in the last few years with new knowledge and speculation about so called "Celts".
How it might be the Roman attack on Gaul that was indeed the "big barbarian invasion"... 
Hi,
I might be missing something, but I had a different impression from reading True Lineage, about the way all those Ex Misc sigils could have changed the vote against Diedne, had they arrived.
Indeed, having chosen precisely that as my Point of Departure, Ex Misc is already placed as not anti-Diedne. Once that vote occurred, those magi vested in the issue would tally up their allies and enemies and act accordingly. House Tremere, for example, would reasonably classify anyone who voted for Diedne to be antagonists that should either be coopted, suborned or defeated. House Diedne, in turn would form stronger bonds with their supporters. After two centuries of such treatment, a mild tendency is deepened into a standing tradition.
I don't see EM as Diedne in disguise. The Diedne might not be good guys, they might be even worse than the Tremere thought they were. (Conversely, the Diedne tradition might be a kind of Holy Magic, snuffed out by the Latin magi, the same way that Rome crucified Christ and burnt the Temple. And killed those poor Dwooids. (Would a Star Wars/Ars Magica crossover feature druids rather than droids?)) And EM is hardly unified.
Still, the diverse EM traditions tend to be disparaged by the mainstream Houses. Even Pralix's lineage is all about preserving the diversity of Ex Misc. If those magi voted to uphold Diedne, as they did in my PoD, it might be said to have been on the general principle of "we don't want to be next" rather than "we are all Diedne." To anyone who hates Diedne, these magi thereby become "the friend of my enemy.
considers
That's more than reasonable. During the two centuries since the Schism War didn't happen, there's all kinds of room for alliances to shift. That could be more interesting, with the Order slouching toward a Schism War whose fault lines run through individual Houses, perhaps with more than two sides.
Anyway,
Ken
Two centuries is like 2 generations considering how long magi live.
Hi,
They aren't. But real world historians often emphasize the knowledge and perspective gained by (western) Christendom through contact with Muslim civilization during the Crusades as critical to its development.
They certainly are not the only potential source of enlightnment, except that India and China are not reasonably attainable. A Faerie civilization might do, I suppose.
Europeans could certainly have developed all this without a clash of civilizations, but probably much more slowly, hence my assumption.
Exactly. My proposal is a kind of "start and happen differently."
Anyway,
Ken
Hi,
More like three or four, if a magus trains his first apprentice no later than 50 or 60 years after Gauntlet. How does your perspective of the world compare to that of your great-grandmother?
(In an Order with simmering conflict, magi might also not live as long.)
Anyway,
Ken
Old views are generally held until the person Dies.
Hi,
Sure! But views shift across generations. My views differ from my father's which differed from my grandfather's....
Anyway,
Ken
They probably would, but not because the two houses were buddies.
Thats probably oversimplifying the order politics and especially Tremere politics far far too much.
"-You´re either with us or against us" was not the common norm at the time. Far from it.
Well the contacts would still mostly be there through trade instead of warfare and that could even potentially lead to more earlier contacts with Persia, India, China and Japan. And that could very well give development a good push forward much EARLIER than historically.
Trade will benefit from less warfare, and trade will potentially spread knowledge much faster than warfare.
The same is quite possible other ways as well, point being that the assumption of a less developed Europe is a very very shaky one.
The lack of warfare would most likely not slow development down at least.
Not as long as the moslems are right on the main trade routes to Asia.
Hi,
Trade had been going on since before the fall of Rome. Trade continued through the 'Dark Ages' with interruption mostly due to events in China and Asia.
Right or wrong, many historians point to the Crusades as a major turning point in European development. The Crusades are credited with causing an increase in trade, among other things.
Suggesting that this development would have been slowed without the Crusades can only be conjecture, but hardly "very shaky."
Anyway,
Ken
Just want to point out two things people keep overlooking.
The Diedne are not Druids. They are an outcast offshoot of Druids. The "real" Druids may be still out there. And Druids, in my mind, would not be experts in Spontaneous magic at all. Julius Ceaser described the Druidic magical tradition as being extremely complicated and involving lengthy rituals. Yes, Druids should be specialized in Ritual magic to be more authentically historic.
Human Sacrifice is not against the Code. What of it? They are our grogs, they volunteered for it / were found guilty of crimes and sentenced to be executed. Appalling? Yes. Cause for War? Certaily, bring it on. But perfectly legal according to the Oath and Code. The Quaesitors are the true criminals, for they violated lawful proceedure. The matter should have never been brought before Tribunal.
Personally, I think the whole thing, top to bottom, was engineered by House Tytalus. Premise of the thread, what if the Primus x-Miscellanea made it on time? My answer is that the puppet masters of House Tytalus had a back up plan, and things whould have gone down the same way. I ask you all, "Que Bono?". Who profits. Rather, who profited? Who gained the most out of the Schism War? House Tytalus. They grabbed most of the spoils, diverted all attention away from their transgressions, and put House Tremere is the misfortunate position of having suffered the greatest losses and carrying the burden of blame.
Hi,
Worth quoting in full:
slow grin
I like this.
(I like other readings too, but I do like this. Hell, the Diedne might never have had anything to do with Druids.)
House Guernicus also came out well, better even than Tytalus. Sure, Tytalus got most of the obvious resources, but House Guernicus runs the Order.
It even fits the House Tytalus writeup, with Guernicus and Tytalus in covert cahoots.
Winners:
Guernicus
Tytalus
Flambeau -- they got what they wanted
Ex Misc (also Tytalus! 
) -- with Diedne gone, they are the exception that proves the rule.
Losers:
Diedne -- obvious
Bonisagus -- Trianomans didn't lead, Bonisagi didn't provide the interesting magics. Their importance to the Order hasn't been the same since.
Bjornaer -- they have become more Latinized and less wild. They are less of what they were. The Guernican program to tame them continues to this day.
Jerbiton -- Increased Guernican policing plays poorly with their desire to live fully in the world.
Mixed:
Tremere -- They took heavy losses, but no one remembers the Sundering anymore. They also have a reputation of Do Not Fuck with Us.
Criamon -- Their ideals didn't prevail then, but magi are a lot less likely to wage war today. Was anything learned, or will all this be repeated?
Merinita -- Arcadia sure looks nice.
Mercere -- War is good for business. Peace is good for business. Neither rain nor shine nor sleet nor hail nor fire from above....
Verditius -- Fewer magi to sell to, more Guernican oversight, but supplying both sides was profitable and there has been a lot of damage. A shame about those lost enchanted items--wanna buy something new and shiny?
Anyway,
Ken
This makes an evil sort of sense. Very twisted... I like it. 
Though I would still argue that peace would have been ex Miscellanae's preferred goal. Even an Haruspex cannot see the future as such. He can see what might be, especially what is inevitable but not what will be. Eg the outcome of the war. Too many free wills interfering in that.
And they were not latin and scarcely christian themselves and suppressed at that time by the latin/christian houses. In fact their low reputation hasn't changed.
Being in fact diabolists, the diedne slowly manage to take over and/or corrupt the whole order of hermes?
Ok, I go out 
Do you know that this actually makes sense?
I love this idea 
Alternative history: The Church and the Nobles actually notice hundreds of magi throwing fire, lightning and other assorted destructions upon themselves and other hapless people. They take steps to eliminate these obviously corrupt perversions of Hell...
I rationalised that through Ceremonial Magic. I do know what you mean, and I personally think that there's a lot to be done with the background, magic, and heritage of the Diedne. I think their magic is more interesting if it isn't just "the magic of the druids", and I think the structure and culture of the house can be far more interesting than "they were secretly evil", or "they were put-upon fluffies", neither of which does justice to anyone (in-game or out).
I don't see us getting an official treatment of these guys for very good reasons. The best you can hope for is one or more treatments turning up in Sub Rosa, from which you pick the one you like best.
I might even do a write-up myself...
Honestly I have a hard time finding this flow of events believable for a few different reasons. If your initial POD is the successful arrival of the EM Primus, as others have stated, assuming that they would have block voted in favor of Diedne would be IMO another 'large' possible POD.
However for these purposes if we assume that they did then what follows is not, IMO, a logical flow of outcome/results from the proceedings.
The Tremere would not have been punished for bringing a issue to vote at tribunal. Accusing the Diedne and trying to vote them down is a legal action that, if it fails, would have zero direct backlash on them.
Prior to the declaration of war violent actions taken by the various Magi trying to 'crack the nut' of the Diedne secrecy are stated to have been conducted under the pretext of wizard wars and judicious use of certamen etc. Now, I freely grant, some of said wizard wars used as pretext may have been flimsy. But they were properly declared and often observed and assisted in execution by Qs. The whole point was providing themselves legal protection for their activities.
My point is that unless there was a massive political disapproval, in a clear and blatantly large majority, these activities would not have been perceived as 'breaking the peace'. Indeed they would likely have continued after the tribunal verdict. That majority didn't exist, as indeed the entire issue of the war is described as having been a close vote. Trying to censure one or the other side if the vote failed would have simply sparked the factions into fighting anyway.
Also the various allies of the Tremere would not have just suddenly switched sides in the fight simply because that one particular vote failed to pass. This issue was not an opportunistic 'fight of the day' type of scenario for the Fs for example.
The way this is described there is a strong undercurrent of hostility building already, in a variety of corners, toward the Diedne for several different reasons. This doesn't evaporate with one failed vote. It festers, possibly leading the dissolution of the Order, likely a continuance of small scale fighting regardless, and probably leading to a pogrom of select wizard wars throughout the tribunals leading to a much more 'palatable' vote next time.
My major point is that this scenario seems to dismiss the perceptions/hostilities present in the various actors on the scene toward Diedne as being merely present in the Tremere and/or having simply vanished in the failure of the vote for war.
IMO the /only/ way Diedne could survive this event is to open up to investigation the way Tytalus did and then conclusively /prove/ that they are innocent of diabolism. Anything else and the agitators still have the original complaints against them to keep agitating. If the vote was so even, as it is described to be, and one can assume the sigils cast by EM would have been similarly split... then a failed vote would just be even more dividing to the Order.