Of course, I'd never suggest a single-cause explanation. And as someone else pointed out, there were lots of advances happening before 1453 as well. I think the sack of Constantiople really threw gas on the coals though.
It was an exceptional event. Most wars in that era were nobles fighting over thrones; the Islamic invasions were a bit more intense than that in that they were from a totally separate religio-cultural tradition and would overturn the entire power structure and ultimately even push peasants to convert.
In a war between kings of the same religion, the priests/imams and lower nobles (i.e. intellectual and writer classes) could potentially stay in their posts even as the front line moved over them. Not so true when it's an entirely different religion.
I think “Islamic Invasions” is a bit too broad of a term. You are referencing the Ottoman Turks specifically.
The funny thing is that Ottomans saw this whole event through a very different lens. They didn’t call themselves the Ottomans or Turks. They, along with their predecessors The Sultanate of Rum (Rome), and the Seljuks, considered themselves the continuation of the Roman Empire.
After the conquest of Constantinople, Mehmed II crowned himself the Caesar of the Roman Empire.
Turks waged a war of expansion to reclaim the Roman Empire for themselves. The religion was just a side effect.
Yeah I guess the calling it a cultural continuation of Rome is wrong.
It's kind of hard to describe this in words because "culture" implies so many things like language, customs, and religion. The "Turkish Rome" didn't really inherit any of those traits.
However, while this probably originated just as a manufactured claim, a casus belli for the Roman lands, over time it seems to have still evolved into something a bit more. Owning Constantinople didn't make people Roman in terms of culture, but it did make them an empire. Sulatane of Rum existed next to Rome for many years and seems to have considered itself a "better Rome than existing Rome".
Makes me think of a parallel with the Holy Roman Empire, which similarly clung on to the title, but not the culture of Rome.
"After the conquest of Constantinople, Mehmed II crowned himself the Caesar of the Roman Empire."
Well yes, that's how feudal systems work. If you take over a country, you get to have its titles. This is how e.g. an English king could conquer Scotland and crown himself king of Scotland. It doesn't mean he always identified as Scottish.
The language "reclaim the Roman empire" is really a stretch since it implies that the Ottomans had some sort of self-image as the natural heirs to Rome before they took Constantinople. Is there any evidence for this?
Why would they need to conquer Constantinople to do this, given that the Byzantines weren't trying to conquer, y'know, actual Rome?
I'm not saying you're wrong. People come up with lots of rationales for wars. And claiming historical right is a popular one, but that goes alongside other motivations as well.
My outside-view assumption would be that this is modern-day politically-motivated interpretation. These days, progressives rules the universities and the history departments. Therefore, they want to advance progressive goals. The see Muslims as a victim class, which means they don't want Islam to be seen in a negative light. Therefore, they would want to avoid historical interpretations wherein Muslims are conquering for self-understood religious reasons like ISIS did so recently. So I think they'd come up with something like, "Oh no, the Ottomans just wanted to reclaim their Rome."
Any time you read history you need to take into account the incentives faced by the people writing it.
In any case, when I refer to Islamic invasions I'm referring to the whole string of them going back to the Abbasid Caliphate - the conquest of Egypt, Arabia, Persia, all of north Africa, Spain, India, etc etc motivated by a self-declared doctrine of holy war (itself used for political ends by individual rulers, of course). I see Constantinople 1453 as just one small episode in this 1400-year story.
The Byzantines (I prefer to call them the ERE, but I'll call them the Byzantines as it's more recognized in lay discourse) had been under threat for a long time, and if the Turks hadn't sacked Istanbul/Constantinople, some other polity would have. Western Europeans sacked Istanbul/Constantinople in 1204 and ruled it as part of the Latin Empire until 1261, when it was retaken. The Byzantines ran into trouble with the Bulgarian kingdoms and the Kievan Rus constantly, along with their Islamic neighbors. If it wasn't the Turks it would have probably been the Bulgars or the Rus.
It was an exceptional event. Most wars in that era were nobles fighting over thrones; the Islamic invasions were a bit more intense than that in that they were from a totally separate religio-cultural tradition and would overturn the entire power structure and ultimately even push peasants to convert.
In a war between kings of the same religion, the priests/imams and lower nobles (i.e. intellectual and writer classes) could potentially stay in their posts even as the front line moved over them. Not so true when it's an entirely different religion.