So let us begin.
If you find some of my answers confusing, don't hesitate to ask for clarifications for much of the matter concerning early medieval period in Croatia is and anyone try to preach something as a gospel either has an agenda or is using romantic history from late 19th early 20th century.
I will start with your major PoD. What you are suggesting are events that came to pass OTL just a decade later than what you would like. The level of centralisation of Croatia in late 11th century is pretty much unknown. We know there was a hierarchy including the King, viceroy, counts and captains but how much autonomy each had from the king is unknown. In the 11th century there were at least 20 counties (I am using english terminology for easier understanding) and it is suggested three of those formed a special area ruled by the viceroy but that is based on a report coming from the 2/4 of the 10th century and doesn't necesary coresponds to the sitation 150 years later.
As far as proces of feudalisation is concerned it seams based on current evidence that most of the above mentioned counties were tribal or clan based and later from the leading families of each of the clans a hereditary feudal system will rise, we only get glimpses of that from the few meager documents that survive and nothing can be said for sure. What is interesting is that once the main branch of the croatian royal line died out and Arpad successors tried to asert their claim local lords showed quite a lot of power and acted as if the soveirgnty of the kingdom rests with the gathering of the clan elders (our parliment grew out of that) rather than with the persona of the king.
As for your question, at least in those time greater centralisation allowed for an easier takeover rather than opposite.
There are very few evidence on that. Material finds are meagre since Croats became christians and there are no writen documents on it. Based on what we know I would speculate it was very similar to what other peoples around the Adriatic had with a stronger influence coming from the west than from the east. Oh and cavalry was apparently Croatian thing as far as south slavs are concerned.
How many troops could be mustered is unknown, for the 10th century we have a byzantine document De Administrando Imperi, which was an internal document writen to help the future Emperor, telling us Croatia could muster 100 000 infantry, 60 000 cavalry, 80 larger ships and 100 smaller ship in times of war and that is quite a lot. How much that is exageration is unknown and though many historians dismis these numbers as untrusworthy I myself wonder why would Konstantin VII leave his son false data on the armed strength of their ally but also a potential enemy.
That is a million dolar question. And the answer is at the same time none and many, because we are not sure what exactly means to be a Croat back than. There certainly was a Croatian identity and was linked to the royal familiy and the 12 noble clans (number 12 is an extrapolation based on info coming from later times, in the begining there could have been more or less of them, we just don't know).
What we know that as far as 2/4 of the 10th century there were people that could be recognised as Avars what ever that should mean, because we are not really sure what it means to be an Avar and how exactly does one distinguish an Avar from a Slav or German dressed as an Avar and vice a versa, just based on material evidence.
Croatian culture belonged to the Adriatic coine, and things weren't that much different on the two shores of the sea. It was a mix of local slavic traditions and tastes, with a heavy dose of Frankish (later Germanic) influence and a slightly lighter sprinkling of various byzantine fashions.
All slavic languages including Croatian have a feature that they easily change foreign names into form conforming to the laws of their language so over a generation or two they would be slightly changed and within a century they would feel natural to a Croatian speaker, but linguistics really isn't my thing though it fascinates me. Someone like the Profesor would probably more of a help with that.
Croatian titles for the head of state until the very end of Trpimirović royal line are unknown and only after they die out we get a stone document calling the head of state in croatian = KRAL = King
Before Croatia became a kingdom (officialy in 925. but that is just an arbitary year based on the papal later from that year calling the ruler of Croatia, rex=king) the exact name of the title is unknown. Rulers of croatia are usually called princes or KNEZ (but that is also arbitrary) for these are "translations" of latin Dux, Dominus, Regnum and Comes.
Generaly speaking
Kral/Kralj = King
Knez = Prince (but the title is only atested in a later period)
Župan = Count
Tepčica = Chamberlin (but we are not 100%)
Ban = Viceroy (though there are people saying latin Dux should be translated as Ban rather than Knez)
Vojvoda = Duke (but the title is only atested in a later period)
Vladanje = Ruler - but this is based on the translation of a latin text so it is iffy
From that period we have very few noble families that are mentioned in contemporary documents and they are still called noble clans/tribes. These are Lapčani, a noble clan to where daughter of King Zvonimir was wed. Snačići, a noble clan from which a Ban Peter (not to be confused with king Peter, sometimes called Peter Svačić, though they might have been the same person) have originated if some later documents are to be belived.
A document form 14th century claims these were the names of the 12 noble clans and what is true is that many later noble families drew lineage and legacy from these clans:
Čudomirići
Gusići
Jamometići/Jamometi
Kačići
Karinjani and Lapčani - these were probably once a single tribe but got divided somehow since they are usualy mentiond as a pair, and count as one choice on the list of 12
Kukari
Lasničići/Lačnićići
Mogorovići
Poletčići
Snačići
Šubići
Tugomirići/Tugomerići
Byzantines saw Croatia in their documents as a vassal but they pretty much saw everyone as that. What is known is they had cordial relations and were allies for most of the time with only two significant conflicts. One in the 9th century when the byzantine fleet raided Croatian coast and the other in the last quarter of 11th century when Croatia join Normans and Pope against Venice and Byznat.
Hungarians and Croatians were competitor over the control of Slavonia that lies between them, but relations in the late 11th were cordial to allied since his Magyar cousins helped Zvonimir fight a Carniolan duke Ulric II. Based on available evidence Magyar and Croatian royal families were quite interlinked and if everything is to be believed king Zvonimir and his wife were cousins related through two different events roughly 70 years in the past.
At that time Serbia was a province of Duklja or Doclea and though today Serbia claims them as part of their heritage the ruling line of those people had an identity separate form a Serbian one though if documents are believed the later rulers of medieval Serbia drew their lineage from these guys. It is much more complicated and could be a source for a debate on its own.
Instead of Italy I will write about Venice since she was the only city of note that could be clasified as Italian in this story. Venice and Croatia were two old enemies stretching back into the 1/3 of the 9th century and often fought. Venice desperately needed the east adriatic coast because it was sheltered and the adriatic sea trade route went alongside it. On the other hand Croatia needed the coast if it ever wanted to be anything more than a kingdom of krast hills and isolated vallies and through out the period stretching from early 9th to the fall of the local dynasty strived to control the coast more than anything else. Not to mention piracy was seen as a legitimate source of income and Venetians did not apreciate that.
What was HRE atitude I couldn't honestly tell because so little is known. There were some skirmishes along the border and a source during the strugle between pope Gregory VII and Henrik IV calls Croats "Popes Myrmidons" and that is basicaly it.
Well we aren't quite sure when Croatia became a kingdom. There are three events:
Father Gotschalk call Trpimir a king in the middle of the 9th century in a document that is the latest writen document discovered about medieval croatian state, it was uncovered in late '30 when it was long "established" that Tomislav was the first king based on the Papal letter dated 925. And then again we have Stjepan Držislav in the last quarter of the 10th century that recieved the crown and palium from Constantinopol. To add to that Zvonimir got a new crown from pope Gregory VII when he swore loyalty to him.
Also becoming the king meant one was becoming King of Croatia and Dalmatia, but only after the reign of Stjepan Držislav. And many historian think that Držislav was actualy the first crowned king based on his christian name Stephen which means Crowned.
The Crown of Croatia or maybe better the Crown of the Croats was all three by the time Arpad family came to power.
The nobility had a mix of western and eastern influences with local differences to suit their tastes and peasants were well peasants, pretty much the same everywhere.
During the reign of Zvonimir Knin was the central seat, but there were others Nin, Biograd, Bijaći, Solin, Klis. But by the late 11th century Knin was emerging as the dominant location just as it was based on the archeological evidence on the turn from 8th to 9th century after which the centre of power mowed to the coast in the area between Split and Trogir.
Not much is left of the medieval town since a later Venetian fort was built atop the citadel and the modern town is built above the suburbium. It was very well defended since it is on a cliff nigh unaproachable and has a spring on top so can endure for a long time as it was shown in the 14th century when the Anjou kings laid siege to it. Knin is also called the "key to Dalmatia" since it sits on a crossroads and control the easiest rout going from western pannonia to the coast.
I hope I answered some of your question, I probably mised something since its late, so feel free to ask some more and I will try and provide answers as soon as I am possible.
Cheers
If you find some of my answers confusing, don't hesitate to ask for clarifications for much of the matter concerning early medieval period in Croatia is and anyone try to preach something as a gospel either has an agenda or is using romantic history from late 19th early 20th century.
I will start with your major PoD. What you are suggesting are events that came to pass OTL just a decade later than what you would like. The level of centralisation of Croatia in late 11th century is pretty much unknown. We know there was a hierarchy including the King, viceroy, counts and captains but how much autonomy each had from the king is unknown. In the 11th century there were at least 20 counties (I am using english terminology for easier understanding) and it is suggested three of those formed a special area ruled by the viceroy but that is based on a report coming from the 2/4 of the 10th century and doesn't necesary coresponds to the sitation 150 years later.
As far as proces of feudalisation is concerned it seams based on current evidence that most of the above mentioned counties were tribal or clan based and later from the leading families of each of the clans a hereditary feudal system will rise, we only get glimpses of that from the few meager documents that survive and nothing can be said for sure. What is interesting is that once the main branch of the croatian royal line died out and Arpad successors tried to asert their claim local lords showed quite a lot of power and acted as if the soveirgnty of the kingdom rests with the gathering of the clan elders (our parliment grew out of that) rather than with the persona of the king.
As for your question, at least in those time greater centralisation allowed for an easier takeover rather than opposite.
There are very few evidence on that. Material finds are meagre since Croats became christians and there are no writen documents on it. Based on what we know I would speculate it was very similar to what other peoples around the Adriatic had with a stronger influence coming from the west than from the east. Oh and cavalry was apparently Croatian thing as far as south slavs are concerned.
How many troops could be mustered is unknown, for the 10th century we have a byzantine document De Administrando Imperi, which was an internal document writen to help the future Emperor, telling us Croatia could muster 100 000 infantry, 60 000 cavalry, 80 larger ships and 100 smaller ship in times of war and that is quite a lot. How much that is exageration is unknown and though many historians dismis these numbers as untrusworthy I myself wonder why would Konstantin VII leave his son false data on the armed strength of their ally but also a potential enemy.
That is a million dolar question. And the answer is at the same time none and many, because we are not sure what exactly means to be a Croat back than. There certainly was a Croatian identity and was linked to the royal familiy and the 12 noble clans (number 12 is an extrapolation based on info coming from later times, in the begining there could have been more or less of them, we just don't know).
What we know that as far as 2/4 of the 10th century there were people that could be recognised as Avars what ever that should mean, because we are not really sure what it means to be an Avar and how exactly does one distinguish an Avar from a Slav or German dressed as an Avar and vice a versa, just based on material evidence.
Croatian culture belonged to the Adriatic coine, and things weren't that much different on the two shores of the sea. It was a mix of local slavic traditions and tastes, with a heavy dose of Frankish (later Germanic) influence and a slightly lighter sprinkling of various byzantine fashions.
All slavic languages including Croatian have a feature that they easily change foreign names into form conforming to the laws of their language so over a generation or two they would be slightly changed and within a century they would feel natural to a Croatian speaker, but linguistics really isn't my thing though it fascinates me. Someone like the Profesor would probably more of a help with that.
Croatian titles for the head of state until the very end of Trpimirović royal line are unknown and only after they die out we get a stone document calling the head of state in croatian = KRAL = King
Before Croatia became a kingdom (officialy in 925. but that is just an arbitary year based on the papal later from that year calling the ruler of Croatia, rex=king) the exact name of the title is unknown. Rulers of croatia are usually called princes or KNEZ (but that is also arbitrary) for these are "translations" of latin Dux, Dominus, Regnum and Comes.
Generaly speaking
Kral/Kralj = King
Knez = Prince (but the title is only atested in a later period)
Župan = Count
Tepčica = Chamberlin (but we are not 100%)
Ban = Viceroy (though there are people saying latin Dux should be translated as Ban rather than Knez)
Vojvoda = Duke (but the title is only atested in a later period)
Vladanje = Ruler - but this is based on the translation of a latin text so it is iffy
From that period we have very few noble families that are mentioned in contemporary documents and they are still called noble clans/tribes. These are Lapčani, a noble clan to where daughter of King Zvonimir was wed. Snačići, a noble clan from which a Ban Peter (not to be confused with king Peter, sometimes called Peter Svačić, though they might have been the same person) have originated if some later documents are to be belived.
A document form 14th century claims these were the names of the 12 noble clans and what is true is that many later noble families drew lineage and legacy from these clans:
Čudomirići
Gusići
Jamometići/Jamometi
Kačići
Karinjani and Lapčani - these were probably once a single tribe but got divided somehow since they are usualy mentiond as a pair, and count as one choice on the list of 12
Kukari
Lasničići/Lačnićići
Mogorovići
Poletčići
Snačići
Šubići
Tugomirići/Tugomerići
Byzantines saw Croatia in their documents as a vassal but they pretty much saw everyone as that. What is known is they had cordial relations and were allies for most of the time with only two significant conflicts. One in the 9th century when the byzantine fleet raided Croatian coast and the other in the last quarter of 11th century when Croatia join Normans and Pope against Venice and Byznat.
Hungarians and Croatians were competitor over the control of Slavonia that lies between them, but relations in the late 11th were cordial to allied since his Magyar cousins helped Zvonimir fight a Carniolan duke Ulric II. Based on available evidence Magyar and Croatian royal families were quite interlinked and if everything is to be believed king Zvonimir and his wife were cousins related through two different events roughly 70 years in the past.
At that time Serbia was a province of Duklja or Doclea and though today Serbia claims them as part of their heritage the ruling line of those people had an identity separate form a Serbian one though if documents are believed the later rulers of medieval Serbia drew their lineage from these guys. It is much more complicated and could be a source for a debate on its own.
Instead of Italy I will write about Venice since she was the only city of note that could be clasified as Italian in this story. Venice and Croatia were two old enemies stretching back into the 1/3 of the 9th century and often fought. Venice desperately needed the east adriatic coast because it was sheltered and the adriatic sea trade route went alongside it. On the other hand Croatia needed the coast if it ever wanted to be anything more than a kingdom of krast hills and isolated vallies and through out the period stretching from early 9th to the fall of the local dynasty strived to control the coast more than anything else. Not to mention piracy was seen as a legitimate source of income and Venetians did not apreciate that.
What was HRE atitude I couldn't honestly tell because so little is known. There were some skirmishes along the border and a source during the strugle between pope Gregory VII and Henrik IV calls Croats "Popes Myrmidons" and that is basicaly it.
Well we aren't quite sure when Croatia became a kingdom. There are three events:
Father Gotschalk call Trpimir a king in the middle of the 9th century in a document that is the latest writen document discovered about medieval croatian state, it was uncovered in late '30 when it was long "established" that Tomislav was the first king based on the Papal letter dated 925. And then again we have Stjepan Držislav in the last quarter of the 10th century that recieved the crown and palium from Constantinopol. To add to that Zvonimir got a new crown from pope Gregory VII when he swore loyalty to him.
Also becoming the king meant one was becoming King of Croatia and Dalmatia, but only after the reign of Stjepan Držislav. And many historian think that Držislav was actualy the first crowned king based on his christian name Stephen which means Crowned.
The Crown of Croatia or maybe better the Crown of the Croats was all three by the time Arpad family came to power.
The nobility had a mix of western and eastern influences with local differences to suit their tastes and peasants were well peasants, pretty much the same everywhere.
During the reign of Zvonimir Knin was the central seat, but there were others Nin, Biograd, Bijaći, Solin, Klis. But by the late 11th century Knin was emerging as the dominant location just as it was based on the archeological evidence on the turn from 8th to 9th century after which the centre of power mowed to the coast in the area between Split and Trogir.
Not much is left of the medieval town since a later Venetian fort was built atop the citadel and the modern town is built above the suburbium. It was very well defended since it is on a cliff nigh unaproachable and has a spring on top so can endure for a long time as it was shown in the 14th century when the Anjou kings laid siege to it. Knin is also called the "key to Dalmatia" since it sits on a crossroads and control the easiest rout going from western pannonia to the coast.
I hope I answered some of your question, I probably mised something since its late, so feel free to ask some more and I will try and provide answers as soon as I am possible.
Cheers
