Post by eurofed on Jan 22, 2020 20:33:36 GMT
This is a thorough (and hopefully improved) revision of a TL I posted sometime ago about a successful Carolingian Empire/Ottonian HRE (the scenario acknowledges a few possible options for the PoD, but soon converges on a common path) uniting Western-Central Europe, and helping the ERE revitalize into a similar degree of success.
This is a world where the Holy Roman Empire and the Eastern Roman Empire experienced decisive success since the Middle Ages and absorbed their respective halves of western Eurasia. The HRE includes the British Isles, France, Iberia, the Low Countries, Germany, Italy, Bohemia, Poland, Hungary, Romania, Croatia-Bosnia, Scandinavia, the Baltic states, part of Belarus and Ukraine, and Northwest Africa. Its vast colonial empire includes most of the Americas, southern Africa, and part of Australasia. It represents Charlemagne's life work gone more successful under his successors than the man himself could hope, bound into indissoluble union by neo-Roman imperial identity, Latin as a common language, and united Latin Christianity. It identifies itself (and the world sees it) as the rebirth of the Western Roman Empire brought about by the Carolingian - or, depending on the alt-historical path, Carolingian-Ottonian - restoration; its citizens may use the 'Western' label or the 'Holy' one depending on circumstances and the preferences of the speaker. The ERE includes Serbia, Bulgaria, Greece, Anatolia, the Levant, Mesopotamia, the Caucasus, western Persia, Arabia, Egypt, Sudan, and Ethiopia. It is bound into indissoluble union by Eastern Roman imperial identity, Greek as a common language, total victory over Islam, and united Greek/Eastern/Oriental Christianity. Its sizable colonial empire includes East Africa and part of Southeast Asia and Australasia. It represents Justinian's heritage reborn stronger than ever after surviving and vanquishing the Muslim onslaught. It identifies itself and the HRE as the legitimate successors of Rome.
The two Roman Empires and the other great powers broadly achieved the same level of socio-economic, cultural, and technological development as the OTL European great powers about a century earlier than OTL. Both the AD and AUC year-numbering systems are widely used across the world, although the Asian empires also use their own systems. Three vast empires (the Holy Roman Empire, the Eastern Roman Empire, and Russia) carved out the northern and western portion of the Old World since the Middle Ages. The Roman empires got busy since the Age of Exploration doing the same to the rest of the world, or at least anywhere Europeans could settle and live comfortably and native civilizations did not successfully resist colonization. For geographical reasons, Russia instead focused on colonial expansion in northern and central Asia, much as its OTL counterpart did. Christianity won a decisive victory in its millennial war against Islam, which only survived in a last few strongholds in eastern Persia, Central Asia, and West Africa. The European empires turned their continent into a global hegemon and brought it to the forefront of the world in terms of wealth, military power, and technological progress. Only the South Asian and East Asian sophisticated civilizations (India, China, Japan-Korea) were ultimately able to keep up the pace with Europe and build empires that could stand up to the European ones as equals.
From a multiverse perspective, historians may agree that the most important turning point leading to the establishment of this timeline occurred when St. Charles I the Great and his successors re-established the Western Roman Empire in Western Europe, stabilized and kept it together, and expanded it to absorb Central Europe, southern Italy, Iberia, and Northwest Africa. There seem to be a few main historical paths that could have produced this outcome. In one branch of them, the Carolingians just got lucky since only one heir per generation survived and no dynastic crisis occurred among Charlemagne's sons, grand-sons, great-grandsons, and great-great-grandsons, starting with the founder’s talented eldest son. This created a strong precedent that made the eventual transition to de jure unitary succession at the beginning of the 10th century look natural in the eyes of the aristocracy and the Church. Alternatively, a division of the Frankish Empire occurred among Charlemagne’s successors that left one successor kingdom much stronger than the rest and able to reunify the Empire in a few generations.
In the latter variant, Charlemagne was slightly more successful at expanding the borders of his domain throughout his reign, so northern Iberia (the Kingdom of Asturias, the northern portion of the Emirate of Cordoba) and most of southern Italy (the Principality of Benevento) were conquered and absorbed in the Carolingian Empire. After his death, instead of the Empire getting split according to the West-East axis that created West Francia, Middle Francia, and East Francia, ultimately evolving into France, Italy, and Germany, it was divided according to a North-South pattern. The result was a Franco-German Kingdom that included northern France and northern Germany (Austrasia, Neustria, Saxony, Burgundy, Thuringia); an Occitan-Iberian Kingdom that included southern France and northern Iberia (Aquitaine, Asturias, the Spanish March, and Provence); and an Austro-Italian Kingdom that included southern Germany and Italy (Bavaria, Swabia, Italy). This division might occur after Charlemagne's death because all three of his sons remained alive and had issue, or after Louis the Pious like OTL as his sons fought among themselves for the inheritance. In this case, however, they adopted a different partition scheme in the Treaty of Verdun equivalent. In either case, superior resources and favorable geopolitical position in the core of the Northern European plain enabled France-Germany to avoid further fragmentation of its domains, consolidate, and gradually reabsorb Occitania-Iberia and Austria-Italy by conquest or peaceful dynastic means.
In both variants, the Carolingian emperors as a rule were strong enough to stand up to their external enemies (Norse, Slavs, Arabs, and Hungarians) when they were on a rampage and take the offensive whenever circumstances allowed it. An expansionist policy got more and more feasible over time as the Empire gradually grew stronger than its enemies could ever be, thanks to military reforms and internal stabilization. They pursued a policy of gradual but steady administrative centralization as well as southward and eastward expansion of the Empire. Successful conquest kept most of the nobility sufficiently busy and content with division of the spoils to stay loyal to the throne.
The second path involved the Ottonians enjoying the same kind of boon, a long streak of steady success and good luck with no serious succession crisis. A century of division, strife, civil wars, feudal chaos, and weakness against external enemies since Charlemagne’s bickering grandsons split the empire persuaded the Western European elites that the Frankish succession system that treated the state as a personal patrimony to be divided among the monarch’s sons was a terrible idea. All the Carolingian successor states that emerged in the century and half since Charles’ death dropped the idea and turned to regard their kingdoms as indissoluble and the succession as unitary. When a dynasty strong, talented, and lucky enough to reunify Western Europe again emerged with the Ottonians in East Francia, they were able to apply the same model to their entire empire without any real difficulty.
Otto I started his family’s great work by stabilizing East Francia, successfully defending it with a decisive victory against the Hungarian invaders, conquering Italy, and establishing the Holy Roman Empire as the union of Germany and Italy. His long-lived son Otto II won the succession war of West Francia, but instead of putting his own candidate on the throne, he picked the crown himself, re-uniting the Carolingian Empire. He reaped just as decisive successes in the Battle of Stilo, bringing mainland South Italy in the HRE, and in the suppression of the Great Slav Uprising, ensuring a steady pace of the Ostsiedlung in the next few centuries. His just as long-lived son Otto III turned the Dukedoms of Bohemia, Poland, and Hungary into vassals, making them subordinate to the HRE in ecclesiastic matters, conquered Sicily, and achieved a detente with the ERE after marrying Byzantine princess Zoe. He stabilized the empire with a series of administrative and military reforms on the Roman model that sent the HRE down a path of gradual but steady centralization. His policy of détente with the ERE and friendly cooperation against the common Muslim enemy established a pattern that with a few inevitable hiccups was to endure in the following centuries and reap excellent dividends for Christianity.
The outcomes of these paths completely converge over time, making a choice between them irrelevant as it concerns the development of the TL. In both cases, the Empire gradually consolidated its Carolingian core and expanded it with the absorption of southern Italy, Bohemia-Moravia, Poland, Hungary-Transylvania, Croatia-Bosnia, and Romania. The HRE took the lead of the Reconquista, and carried it to a successful conclusion relatively quickly thanks to its vast resources. The Empire absorbed all of Iberia and expanded the Reconquista to Northwest Africa using Andalusia and Sicily as jumping points. That region, too, was eventually conquered and forcibly assimilated. The HRE evolved into a solid multi-ethnic nation-state that based its strength on the pillars of a neo-Roman civic-universalist identity, Latin as a lingua franca, and Christianity. It spanned Western Europe, Central Europe, Southern Europe, and re-Christianized Northwest Africa as its core territories.
The Eastern Roman Empire was able to enjoy a fairly similar path of revitalization and continued success thanks to its successful assimilation of the Bulgarians and the Serbs, who were absorbed by the Byzantines after their conquest of the Bulgarian Empire, and the Armenians, who chose to align and cooperate with the ERE to resist the Arab onslaught. The resulting Greek-Bulgarian-Armenian union that spanned Southeastern Europe, Anatolia, and the Caucasus proved strong enough to resist the assaults of Islam and gradually reverse its tide of conquest. The help of the HRE and cooperation between the two Roman empires also proved very important to achieve these results and ensure a decisive success in the fight against the Muslim states.
The HRE and the ERE inevitably experienced a certain degree of imperial rivalry and occasionally engaged in military clashes about the control of various border territories, trading routes, and colonies. Nevertheless, they were able to keep sufficiently friendly relations most of the time, acknowledge each other as sister empires and the legitimate successors of Rome, and achieve a good degree of relatively steady military cooperation against the common Muslim enemy. This allowed Christianity to win back all the areas it had lost to Islam during Arab expansion and conquer even more in the Middle East. Evolution of the Western Church favored this outcome, since it developed a decentralized structure and stayed subservient to Imperial authority much like the Eastern Church in the Byzantine lands.
A strong HRE suppressed the Gregorian Reform, won an overwhelming victory in the Investiture Controversy, and otherwise quashed the ambitions of the Roman Curia and the theocratic faction of the Western Church for political autonomy, temporal power, and papal supremacy. The Latin Church had to accept submission to Imperial authority and the Bishop of Rome got the status of Patriarch with a symbolic ‘primus inter pares’ primacy but no more effective power and prestige than the other Patriarchs in the East and the West. The Church developed a decentralized, polycentric structure that allowed the Latin and Greek areas and the various European states to co-exist in religious communion and loose ecclesiastic union. It also allowed an eventual reconciliation of the Latin-Greek and Eastern Churches during the Christian re-conquest of the Middle East. The resolution of the Nestorian and Chalcedonian schisms considerably eased Christian re-conquest of the Middle East and enabled military cooperation and eventual fusion between the ERE and the Ethiopian Empire.
The outcome proved devastating for Islam, which in a few centuries lost Iberia and Northwest Africa to the HRE as well as the Levant, Mesopotamia, Egypt-Nubia, and western Persia to the ERE. An implacable sequence of parallel or joint Imperial-Byzantine Crusades against Islam eventually conquered all these areas from the Muslim states, imposed their forcible re-Christianization, and culminated in the conquest of Arabia and the destruction of Mecca and Medina. The loss of its holy cities and all its core lands delivered Islam a shock, humiliation, and existential challenge it was ultimately unable to overcome. In its weakened and discredited state, it was unable to keep a significant presence in East Africa, the Indian subcontinent, and Southeast Asia. European colonial expansion with its spread of Christianity and a resurgence of Hinduism and Buddhism gradually nullified all the inroads Islam had made in these regions during its Golden Age.
In the end, Islam was only able to survive in the Persian and Turkic states of eastern Persia and southern Central Asia, where Shia became the dominant branch, and in the Sahelian kingdoms of West Africa. Various factors combined to allow its survival in these marginal areas, including their remoteness and the logistic troubles the Christian empires experienced in penetrating them, their perceived low value since after conquest of the Middle East Europe could easily trade with the Asian civilizations by sea, and the European powers getting distracted by colonization of more valuable areas. Even if it was able to survive in these areas, however, Islam's days as one of the largest-sized world religions, in the same league as Christianity, Hinduism, and Buddhism, were gone forever.
In Northern Europe, Viking raiding created a serious security problem for Western Europe for a while, but relatively soon the growing strength of the HRE became an impassable barrier and forced the Norse to divert their encroachment and ambitions to the British Isles and the Russian lands. This process intensified once the HRE conquered Denmark in an effort to free Western Europe from the threat of Norse raiding. Imperial conquest triggered a mass exodus of Danish refugees to the British Isles and the Russian lands. Apart from this event, the early HRE did not show excessive interest for the North Sea and Baltic Sea region for various reasons including the perceived limited value of the area and the Empire's prevalent focus on domestic issues and southward/eastward expansion. This allowed various independent states to form in the British Isles and the Scandinavian Peninsula.
Over time, however, the region considerably developed, increasing its importance and the value of the North Sea and Baltic Sea trade routes. The HRE's strength and stability also substantially expanded in comparison to the Empire's established commitments, making the Empire significantly more interested and able to project its influence in the area. The result was a sustained effort to secure dominant Imperial control of the North Sea and Baltic Sea trade routes that led to the annexation of Skaneland, colonization of the Baltic States, and vassallization of the Scandinavian kingdoms. Imperial expansion in the region drove the kingdom of England to support the anti-Imperial factions in Scandinavia. This in turn motivated the HRE to regard Britain as important enough to justify into an all-out conquest effort of England, regardless of its other concerns and distractions.
Despite English resistance, the power gap was simply too great; England succumbed to Imperial conquest and the HRE thoroughly pacified it and assimilated in its system. Scotland and Wales initially stayed independent while Imperial forces were busy with the pacification of England, but security and territorial continuity concerns gradually drove the Imperials to extend their conquest to the totality of Britain. As it concerned Ireland, however, the HRE was mostly content to impose a client state relationship on the Irish kingdoms and did not care overmuch to impose its direct rule. Much like it did with the bulk of the Scandinavian Peninsula, it regarded the Emerald Isle as hardly worth doing the effort of conquest. Over time, however, the HRE gradually absorbed the Irish and Nordic kingdoms as well, out of a combination of factors including dynastic lapses, internal crises in a client state driving Imperial peacekeeping interventions, and ideological, religious, and geopolitical momentum pulling the whole of Western Europe into Imperial unity.
This is a world where the Holy Roman Empire and the Eastern Roman Empire experienced decisive success since the Middle Ages and absorbed their respective halves of western Eurasia. The HRE includes the British Isles, France, Iberia, the Low Countries, Germany, Italy, Bohemia, Poland, Hungary, Romania, Croatia-Bosnia, Scandinavia, the Baltic states, part of Belarus and Ukraine, and Northwest Africa. Its vast colonial empire includes most of the Americas, southern Africa, and part of Australasia. It represents Charlemagne's life work gone more successful under his successors than the man himself could hope, bound into indissoluble union by neo-Roman imperial identity, Latin as a common language, and united Latin Christianity. It identifies itself (and the world sees it) as the rebirth of the Western Roman Empire brought about by the Carolingian - or, depending on the alt-historical path, Carolingian-Ottonian - restoration; its citizens may use the 'Western' label or the 'Holy' one depending on circumstances and the preferences of the speaker. The ERE includes Serbia, Bulgaria, Greece, Anatolia, the Levant, Mesopotamia, the Caucasus, western Persia, Arabia, Egypt, Sudan, and Ethiopia. It is bound into indissoluble union by Eastern Roman imperial identity, Greek as a common language, total victory over Islam, and united Greek/Eastern/Oriental Christianity. Its sizable colonial empire includes East Africa and part of Southeast Asia and Australasia. It represents Justinian's heritage reborn stronger than ever after surviving and vanquishing the Muslim onslaught. It identifies itself and the HRE as the legitimate successors of Rome.
The two Roman Empires and the other great powers broadly achieved the same level of socio-economic, cultural, and technological development as the OTL European great powers about a century earlier than OTL. Both the AD and AUC year-numbering systems are widely used across the world, although the Asian empires also use their own systems. Three vast empires (the Holy Roman Empire, the Eastern Roman Empire, and Russia) carved out the northern and western portion of the Old World since the Middle Ages. The Roman empires got busy since the Age of Exploration doing the same to the rest of the world, or at least anywhere Europeans could settle and live comfortably and native civilizations did not successfully resist colonization. For geographical reasons, Russia instead focused on colonial expansion in northern and central Asia, much as its OTL counterpart did. Christianity won a decisive victory in its millennial war against Islam, which only survived in a last few strongholds in eastern Persia, Central Asia, and West Africa. The European empires turned their continent into a global hegemon and brought it to the forefront of the world in terms of wealth, military power, and technological progress. Only the South Asian and East Asian sophisticated civilizations (India, China, Japan-Korea) were ultimately able to keep up the pace with Europe and build empires that could stand up to the European ones as equals.
From a multiverse perspective, historians may agree that the most important turning point leading to the establishment of this timeline occurred when St. Charles I the Great and his successors re-established the Western Roman Empire in Western Europe, stabilized and kept it together, and expanded it to absorb Central Europe, southern Italy, Iberia, and Northwest Africa. There seem to be a few main historical paths that could have produced this outcome. In one branch of them, the Carolingians just got lucky since only one heir per generation survived and no dynastic crisis occurred among Charlemagne's sons, grand-sons, great-grandsons, and great-great-grandsons, starting with the founder’s talented eldest son. This created a strong precedent that made the eventual transition to de jure unitary succession at the beginning of the 10th century look natural in the eyes of the aristocracy and the Church. Alternatively, a division of the Frankish Empire occurred among Charlemagne’s successors that left one successor kingdom much stronger than the rest and able to reunify the Empire in a few generations.
In the latter variant, Charlemagne was slightly more successful at expanding the borders of his domain throughout his reign, so northern Iberia (the Kingdom of Asturias, the northern portion of the Emirate of Cordoba) and most of southern Italy (the Principality of Benevento) were conquered and absorbed in the Carolingian Empire. After his death, instead of the Empire getting split according to the West-East axis that created West Francia, Middle Francia, and East Francia, ultimately evolving into France, Italy, and Germany, it was divided according to a North-South pattern. The result was a Franco-German Kingdom that included northern France and northern Germany (Austrasia, Neustria, Saxony, Burgundy, Thuringia); an Occitan-Iberian Kingdom that included southern France and northern Iberia (Aquitaine, Asturias, the Spanish March, and Provence); and an Austro-Italian Kingdom that included southern Germany and Italy (Bavaria, Swabia, Italy). This division might occur after Charlemagne's death because all three of his sons remained alive and had issue, or after Louis the Pious like OTL as his sons fought among themselves for the inheritance. In this case, however, they adopted a different partition scheme in the Treaty of Verdun equivalent. In either case, superior resources and favorable geopolitical position in the core of the Northern European plain enabled France-Germany to avoid further fragmentation of its domains, consolidate, and gradually reabsorb Occitania-Iberia and Austria-Italy by conquest or peaceful dynastic means.
In both variants, the Carolingian emperors as a rule were strong enough to stand up to their external enemies (Norse, Slavs, Arabs, and Hungarians) when they were on a rampage and take the offensive whenever circumstances allowed it. An expansionist policy got more and more feasible over time as the Empire gradually grew stronger than its enemies could ever be, thanks to military reforms and internal stabilization. They pursued a policy of gradual but steady administrative centralization as well as southward and eastward expansion of the Empire. Successful conquest kept most of the nobility sufficiently busy and content with division of the spoils to stay loyal to the throne.
The second path involved the Ottonians enjoying the same kind of boon, a long streak of steady success and good luck with no serious succession crisis. A century of division, strife, civil wars, feudal chaos, and weakness against external enemies since Charlemagne’s bickering grandsons split the empire persuaded the Western European elites that the Frankish succession system that treated the state as a personal patrimony to be divided among the monarch’s sons was a terrible idea. All the Carolingian successor states that emerged in the century and half since Charles’ death dropped the idea and turned to regard their kingdoms as indissoluble and the succession as unitary. When a dynasty strong, talented, and lucky enough to reunify Western Europe again emerged with the Ottonians in East Francia, they were able to apply the same model to their entire empire without any real difficulty.
Otto I started his family’s great work by stabilizing East Francia, successfully defending it with a decisive victory against the Hungarian invaders, conquering Italy, and establishing the Holy Roman Empire as the union of Germany and Italy. His long-lived son Otto II won the succession war of West Francia, but instead of putting his own candidate on the throne, he picked the crown himself, re-uniting the Carolingian Empire. He reaped just as decisive successes in the Battle of Stilo, bringing mainland South Italy in the HRE, and in the suppression of the Great Slav Uprising, ensuring a steady pace of the Ostsiedlung in the next few centuries. His just as long-lived son Otto III turned the Dukedoms of Bohemia, Poland, and Hungary into vassals, making them subordinate to the HRE in ecclesiastic matters, conquered Sicily, and achieved a detente with the ERE after marrying Byzantine princess Zoe. He stabilized the empire with a series of administrative and military reforms on the Roman model that sent the HRE down a path of gradual but steady centralization. His policy of détente with the ERE and friendly cooperation against the common Muslim enemy established a pattern that with a few inevitable hiccups was to endure in the following centuries and reap excellent dividends for Christianity.
The outcomes of these paths completely converge over time, making a choice between them irrelevant as it concerns the development of the TL. In both cases, the Empire gradually consolidated its Carolingian core and expanded it with the absorption of southern Italy, Bohemia-Moravia, Poland, Hungary-Transylvania, Croatia-Bosnia, and Romania. The HRE took the lead of the Reconquista, and carried it to a successful conclusion relatively quickly thanks to its vast resources. The Empire absorbed all of Iberia and expanded the Reconquista to Northwest Africa using Andalusia and Sicily as jumping points. That region, too, was eventually conquered and forcibly assimilated. The HRE evolved into a solid multi-ethnic nation-state that based its strength on the pillars of a neo-Roman civic-universalist identity, Latin as a lingua franca, and Christianity. It spanned Western Europe, Central Europe, Southern Europe, and re-Christianized Northwest Africa as its core territories.
The Eastern Roman Empire was able to enjoy a fairly similar path of revitalization and continued success thanks to its successful assimilation of the Bulgarians and the Serbs, who were absorbed by the Byzantines after their conquest of the Bulgarian Empire, and the Armenians, who chose to align and cooperate with the ERE to resist the Arab onslaught. The resulting Greek-Bulgarian-Armenian union that spanned Southeastern Europe, Anatolia, and the Caucasus proved strong enough to resist the assaults of Islam and gradually reverse its tide of conquest. The help of the HRE and cooperation between the two Roman empires also proved very important to achieve these results and ensure a decisive success in the fight against the Muslim states.
The HRE and the ERE inevitably experienced a certain degree of imperial rivalry and occasionally engaged in military clashes about the control of various border territories, trading routes, and colonies. Nevertheless, they were able to keep sufficiently friendly relations most of the time, acknowledge each other as sister empires and the legitimate successors of Rome, and achieve a good degree of relatively steady military cooperation against the common Muslim enemy. This allowed Christianity to win back all the areas it had lost to Islam during Arab expansion and conquer even more in the Middle East. Evolution of the Western Church favored this outcome, since it developed a decentralized structure and stayed subservient to Imperial authority much like the Eastern Church in the Byzantine lands.
A strong HRE suppressed the Gregorian Reform, won an overwhelming victory in the Investiture Controversy, and otherwise quashed the ambitions of the Roman Curia and the theocratic faction of the Western Church for political autonomy, temporal power, and papal supremacy. The Latin Church had to accept submission to Imperial authority and the Bishop of Rome got the status of Patriarch with a symbolic ‘primus inter pares’ primacy but no more effective power and prestige than the other Patriarchs in the East and the West. The Church developed a decentralized, polycentric structure that allowed the Latin and Greek areas and the various European states to co-exist in religious communion and loose ecclesiastic union. It also allowed an eventual reconciliation of the Latin-Greek and Eastern Churches during the Christian re-conquest of the Middle East. The resolution of the Nestorian and Chalcedonian schisms considerably eased Christian re-conquest of the Middle East and enabled military cooperation and eventual fusion between the ERE and the Ethiopian Empire.
The outcome proved devastating for Islam, which in a few centuries lost Iberia and Northwest Africa to the HRE as well as the Levant, Mesopotamia, Egypt-Nubia, and western Persia to the ERE. An implacable sequence of parallel or joint Imperial-Byzantine Crusades against Islam eventually conquered all these areas from the Muslim states, imposed their forcible re-Christianization, and culminated in the conquest of Arabia and the destruction of Mecca and Medina. The loss of its holy cities and all its core lands delivered Islam a shock, humiliation, and existential challenge it was ultimately unable to overcome. In its weakened and discredited state, it was unable to keep a significant presence in East Africa, the Indian subcontinent, and Southeast Asia. European colonial expansion with its spread of Christianity and a resurgence of Hinduism and Buddhism gradually nullified all the inroads Islam had made in these regions during its Golden Age.
In the end, Islam was only able to survive in the Persian and Turkic states of eastern Persia and southern Central Asia, where Shia became the dominant branch, and in the Sahelian kingdoms of West Africa. Various factors combined to allow its survival in these marginal areas, including their remoteness and the logistic troubles the Christian empires experienced in penetrating them, their perceived low value since after conquest of the Middle East Europe could easily trade with the Asian civilizations by sea, and the European powers getting distracted by colonization of more valuable areas. Even if it was able to survive in these areas, however, Islam's days as one of the largest-sized world religions, in the same league as Christianity, Hinduism, and Buddhism, were gone forever.
In Northern Europe, Viking raiding created a serious security problem for Western Europe for a while, but relatively soon the growing strength of the HRE became an impassable barrier and forced the Norse to divert their encroachment and ambitions to the British Isles and the Russian lands. This process intensified once the HRE conquered Denmark in an effort to free Western Europe from the threat of Norse raiding. Imperial conquest triggered a mass exodus of Danish refugees to the British Isles and the Russian lands. Apart from this event, the early HRE did not show excessive interest for the North Sea and Baltic Sea region for various reasons including the perceived limited value of the area and the Empire's prevalent focus on domestic issues and southward/eastward expansion. This allowed various independent states to form in the British Isles and the Scandinavian Peninsula.
Over time, however, the region considerably developed, increasing its importance and the value of the North Sea and Baltic Sea trade routes. The HRE's strength and stability also substantially expanded in comparison to the Empire's established commitments, making the Empire significantly more interested and able to project its influence in the area. The result was a sustained effort to secure dominant Imperial control of the North Sea and Baltic Sea trade routes that led to the annexation of Skaneland, colonization of the Baltic States, and vassallization of the Scandinavian kingdoms. Imperial expansion in the region drove the kingdom of England to support the anti-Imperial factions in Scandinavia. This in turn motivated the HRE to regard Britain as important enough to justify into an all-out conquest effort of England, regardless of its other concerns and distractions.
Despite English resistance, the power gap was simply too great; England succumbed to Imperial conquest and the HRE thoroughly pacified it and assimilated in its system. Scotland and Wales initially stayed independent while Imperial forces were busy with the pacification of England, but security and territorial continuity concerns gradually drove the Imperials to extend their conquest to the totality of Britain. As it concerned Ireland, however, the HRE was mostly content to impose a client state relationship on the Irish kingdoms and did not care overmuch to impose its direct rule. Much like it did with the bulk of the Scandinavian Peninsula, it regarded the Emerald Isle as hardly worth doing the effort of conquest. Over time, however, the HRE gradually absorbed the Irish and Nordic kingdoms as well, out of a combination of factors including dynastic lapses, internal crises in a client state driving Imperial peacekeeping interventions, and ideological, religious, and geopolitical momentum pulling the whole of Western Europe into Imperial unity.
