The Mongols would have conquered Europe

I'm going to be arguing that it is highly unlikely the Mongols would have conquered most of mainland Europe. What actually happenedThe princes of the Rus had been fighting each other for about a century, which left the country fragmented and broken. As the old maxim goes, "divided we fall" - and so the Russians did. Almost half a million Russians were slaughtered by the Mongol invaders when they attacked in 1237-1240 (. http://en.wikipedia.org...). The Mongols also had the additional advantage of gunpowder, which took many Russians by surprise. The fighting culminated in the great siege of Kiev, reknown for it's massive walls, except for a single gate partially constructed of wood. The governor of Kiev at the time (who survived the attack) was a man named Dmytro, and he later wrote about his hopes the Mongols would never find the city's Achilles heel. The Mongols bombarded for days and days, before eventually discovering the city's secret. The gate was burned down and the Mongols completely subjugated Russia. This is an important battle - it proves the Mongols did not have the power to break walls as thick as Kiev's with their siege technology. However, the Mongols did not expect their attack on Kiev to last so long. An important Mongol battle tactic was to let people run away so they could focus on the remaining fighters, and then chase after their foes later with their superior speed. Since the "remaining fighters" in this instance had withstood a Mongol siege for a record length of time, the people who ran away (a tribe called the Cumans) made it all the way to Hungary, where they were given protection. Meanwhile, two important things happened. First, a group of Venetian merchants and explorers made contact with the Mongols and came to a trade agreement with them. Venice also claimed they were happy to pay taxes to the Mongols, but Batu Khan explained that wouldn't even be necessary if the Venetians handed over all their maps of Europe (which they were preparing to do as the Mongols retreated). The point is that it is unlikely any Mongol raid into Europe would have gone through Venetian territory. Secondly, all the other nations of Europe, which at that time were predominantly Catholic, equated the Mongols with Tartars (what some Chinese called them), which sounded like they came from Tartarus, the latin for "hell". As a result, they felt a religious conviction to fight the Mongols. The Mongol invasion of Poland and Hungary is the most interesting. Poland was defended primarily in a battle outside Liegnitz (. http://en.wikipedia.org...). They had the support of the Pope, who had come to hate the Mongols. The Mongols had little interest in winning, as the primary reason for the invasion was to prevent support from reaching their main invasion into Hungary. Each tried their usual battle tactics. Long story short, the Mongol strategy proved an effective counter-strategy to the European one. In Hungary it gets still more interesting. The Mongol strategy essentially involved crossing a major river (. http://en.wikipedia.org...) but the king of Hungary stopped them with his technologically superior crossbows, and routed the Mongols. Later, the Mongols won the battle by building a secret bridge while distracting the Hungarian king. Gunpowder was almost certainly deployed in this battle also. The next Mongol target was the Danube and Croatia. The Mongols had not made it far into these places before their retreat. What these early battles demonstrate is two things. First, Mongol gunpowder and weapons were fairly ineffective. Second, Mongol strategy was far superior. What I think would have happened nextUnlike Russia, in Western Europe the Mongols faced a united front (except for tiny Venice, who were squabbling with the Pope over land anyway), joined by religious conviction more than fear. The cities of Europe were amongst the most fortified in the world, many major castles having walls matching those at Kiev but without the weaknesses. Furthermore, in Western Europe it was impossible to maintain a Mongol-style supply line because of the lack of wild horses, most of which had been long put to use in agriculture. With the religious fervor of the age, farmers would likely have killed their horses before the Mongols got to them. The Cumans had long told the Europeans how a Mongol supply chain works. Furthermore, any supply line could have been easily flanked. Finally, horses couldn't fight so well in North-Western Europe. The Hundred Years War provides numerous examples demonstrating this. Mongol bows also could not function properly in wet weather. Europeans knew that they had fortifications and superior missile weapons. Here's my scenario. The Mongols would likely have taken Croatia (despite suffering many more major losses along the way, like they did trying to assault Klis Fortress) and hired Venetian ships to attack Sicily. Meanwhile, a second detachment attacks the Holy Roman Empire, aiming for the South to make ambushes easier for them, relying on a decent system of military intelligence, with the hope of cutting off the more densely-populated north. Sicily would have had the support of most of the Italian states, as well as France. Italian armies of the era were mostly composed of spearmen, composite crossbowmen, and a few heavy cavalry. I imagine the heavy cavalry would have dismounted. Here they would have met fortifications like this:. http://www.artist-embedded.org...Such a location is incredibly hard for horsemen to assault from a ship. They would need to make landfall, with their horses. Since each Mongol soldier had five horses, this would mean carrying the equivalent of about 7 people for every Mongol soldier. With ships the size they were back then, this would have taken at least a month. During this time, each time one group is sent over, the combined forces of southern Europe would have destroyed the units one by one. If the Mongols took only a single horse each, they would lose their advantage of manuverability. The rocky terrain would have made it easy for sniper-crossbows to take down the horses. In Southern Germany, the Mongols are likely to have faced a sea of castles and walls, with the Europeans wishing to avoid a field battle until they knew for a certainty where their enemy was, and the Mongols knowing that they were no match for European walling. Bohemia, meanwhile, would be free to destroy the Mongol supply chain with the 20,000 men that didn't quite make it in time to defend Poland. Cut off in a desolate wasteland, the Mongols would be forced to retreat and suffer heavy losses along the way. Even if the Bohemian army was somehow routed, the sheer number of states that could fulfil the role of cutting off the Mongol supply line (half the states of the holy roman empire, denmark, sweden etc) makes it quite likely somebody would have done so. My opponent is free to imagine any alternative history and I will entertain it, but from my study of Mongol tactics I think a two-pronged assault seems most likely if they wished to avoid Venice. It also would fail, regardless of whether Ogedai had died or not. I look forward to reading my opponent's opening case.