No, I'm pretty sure the 1274 defeat was mostly (if not solely) defeated by weather. As for 1281, I know the fighting was more difficult and less likely to succeed, but I think it could still be attributed to weather as well. Again, I'm not sure, but some quick research (Google Books) shows the Japanese succeeding in keeping the Mongol invasion in check for two months, and then the typhoon hit and destroyed the Mongol force right before reinforcements could land. It makes sense. I mean, if the Japanese were winning, why would they attribute their success (in retrospect) to the kamikaze?Actually at least one of the attacks on Japan was being defeated before a storm scattered the invasion force. Another one didn't get that far and the Japanese decided to emphasis the divine nature of the intervention for political means. However its unclear whether the the Mongols could have taken Japan and it would have required some very hard fighting. Note that since many of the forces involved were Chinese or Korean then it may be inaccurate to refer to them as Mongols, especially in the sense of steppe horsemen.
I think in 1274, there were Korean sailors for the boats, but I think the majority of the fighting forces on land were Mongol. I could be wrong. The 1281 one had Koreans and Chinese fighting in the Mongol force as well, but then again, many Mongol armies had local peoples fighting with or for them as well. People talk all the time about how "the Mongol conquest of China" and rarely talk about "the Northern Chinese, Mongol-directed conquest of Southern China," even though the Southern Song was conquered by Chinese troops too.
But even then, that wasn't my main point. I was just pointing out that, when they needed one, the Mongols could build a navy. I'm not saying that the Mongols would develop a navy so they would have control of the sea during a siege of Constantinople, but I am taking aim at the assertion that the Mongols would be automatically thwarted by any body of water.
I don't know too much about the Byzantine-Arab wars, but I was asking if the Byzantines employed scorched-earth tactics every time they were faced with an invasion of Asia Minor. For example, did they employ a scorched-earth tactic to repel the Seljuks?This suggests that you know little of the history of Byzantium/Caliphate conflicts. While there were occasional truces there were frequent large scale raids and invasions most years. Even when the Caliphate splintered this in one way made matters worse as peace with one Muslim faction wouldn't necessarily mean peace with others. This conflict was by sea as well as land with the empire losing Cyprus, Crete, Sicily and many other islands, although a number were regained by 1025. Also it meant that the empire had to be on its guard at just about every point.
. I guess. I didn't say this campaign would be leisurely on the Mongols' part. However, I should point out that this scenario assumes that the Byzantium has strong rulers and a good command. In my opinion, in some ways this is acceptable, but at the same time, I feel this unfairly implies that the Byzantine Empire won't be affected by the constant intrigue and civil disturbances that characterized it historically.The Mongols could be very flexible. In terms of food the key point with the Seljuk's was that the blow came against a gravely weakened empire, with the army eviscerated by political opponents and the government split by divisions. As such, especially after the defeat at Manzikert, there was nothing to stop the Turkish advance, especially since the remains of the imperial government was fighting against itself for power.
I think Elfwine is possibly being a bit optimistic but from what's been said he definitely knows more about the history of Byzantium than you. A lot would depend not only on the size of the empire at the point of the clash but also how well led and stable it was. If under a strong emperor and capable command as in much of the 10thC then even a combined attack from both Mesopotamia and the Ukraine won't necessarily break the empire, although any class with the Mongols in this time period is going to be difficult and costly.
I suspect the threat from the south would be the greater as it is across good terrain for the Mongols and they would very likely lose border areas such as possessions in Syria while whether the Mongols could force the passes into the Anatolian heartland would probably be the key factor. If so they are likely to devastate much of it but probably less likely to stay than the Turks.
From the north the terrain is less favourable to the Mongols. It won't greatly impede their crossing but staying and maintaining the vast numbers of horses their military style needed is likely to be very difficult for any length of time.
How about this for a scenario: the Mongols would focus their attempts from the east of Constantinople, in Anatolia. However, I also suggest that if they conquer Ukraine and the areas to the north of the Black Sea, that Mongols might frequently raid the areas west of Constantinople (what is now Bulgaria, Greece, etc), before returning to the steppes, so as to force the Byzantines to divert their attention in two.
I too don't see Mongols in Anatolia for too long, in the sense that I don't think there will be a Mongol Anatolia in place of a Turkish Anatolia, but I really don't see the Mongols failing to take the territory that was overrun by horse nomads historically. Yes, the Byzantine loss is attributed to civil strife, but even if you take out the civil wars and make Byzantium stronger, they're also facing a stronger opponent.
Again, I'm wondering why the Byzantines would have the ability to stop the Mongols, given how the Mongols managed to conquer other countries experienced in fighting steppe nomads.