Beginning as OTL
At the time around the PoD one of, if not the major power in Europe, the Angevine Empire ended with the Battle of Bouvines in 1214, which France won. As a consequence, John Lackland had to grant the Magna Charta in England in 1215. The pattern soon repeated: In 1259 England lost all possessions in France but Guyenne, and the new uprisings of the barons 1258-65 forced the king to accept the Oxford Provisions.
Divergence and first Aquitainian War
1290 - the very year when the Jews were evicted from England - in Scotland, the young queen (nine years) died. King Edward I interfered for the succession, John Balliol became new king. But 1297, war between England and Scotland began. 1298, the Scottish uprisings under William Wallace started. 1307, Edward I died, but not before having defeated the Scots twice (not just once as OTL). During the 1310s, however, the Scots defeated the English, thanks to their pike fighters. TTL Edward II started in a better position, and wasn't as incompetent as his OTL counterpart, but after many fights he got tired too. So the Scots became independent again, only had to cede the territory south of the Firths (Wall of Antoninus), which was Anglified very much in the following centuries.
While there was no Hundred-Year War as OTL, England and France still managed to find an opportunity to fight. In 1341, the Breton War of Succession began. France supported Charles of Blois, England John of Montfort - with the result that both were drawn into the war, which now became the First Aquitainian War. 1345, Scotland entered the war against England, hoping to get the lost lands back. But thanks to their longbows, the English defeated the French several times. In 1353, France has to make peace with England after the defeat in the battle of Caen. John of Montfort became duke of Brittany, England got all of Gascony (similar as in the peace of OTL 1360), Flanders acquired the Artois; now free to make war against Scotland, the English defeated them soon. The pre-war border was restored.
In 1366, the French started the war against England again. Since they had learned how devastating the English / Welsh longbows were, they avoided open fight - with success. In 1385, England and France made peace again; the English lost what they had conquered in the last war, going back to the borders of 1340.
1397/98, England was struck by the Black Death.
In 1414, new king Richard III made alliances with Castille and the Netherlands, attacked France again. The Second Aquitainian War had begun. After initial successes, 1421 France made a separate peace with the Netherlands, giving emperor Gerhard II Flanders, which was incorporated into the Netherlands. Now, the tides turned again: Storming the conquered cities with cannons and relying on their greater manpower, the French slowly drove the allied English and Castillians back. 1424, Castille left the war too. However, when in 1426 the pope and the Anjou king of Naples asked the French king for a crusade against the Rum-Seljuks, king Charles IV agreed. He made peace with the English, leaving Guyenne in their hands; king Richard III had to accept it as a fief, though.
During the 1430s, unrest among the peasants in England spread, which kept the king and the nobles busy after the lost war. The unrest was also religiously motivated - a William Aston had translated the bible into English.
Out of France, into the New World
In 1455, king Louis XII of France had his completely mad younger brother Philippe (also duke of Bourbon) killed. The nobles (including the royal sidelines, and old king Richard III of England, who was talked by his advisors into it) who were already concerned with the growing power of the king, used this accident to rebel against him. 1460, the first French Civil War ended, Louis' other brother Charles V became king. He had to grant the other dukes a lot of power, however, which made them practically independent.
In a short war 1463/64, England defeated Scotland, took their colony of New Scotland in Atlantis, which was renamed New England, of course. The capital of the colony, Perth beyond the Ocean, was renamed after the winner of the battle, Boston. England slowly extended its settlements, until they went from OTL Bar Harbor, Maine, to New Haven, Connecticut.
1477-83, the third Aquitainian War took place, which ended with Aquitaine finally becoming French. Scotland-Norway also had entered the war on France's side, but to their disadvantage: In 1487, the English took the Scottish capital of Perth; king Daibidh V and his three sons had to flee to Norway. The Shetland and Orkney islands became English, too.
The Quadruple Monarchy and Triple Monarchy
|King: Edward V Plantagenet
Religion: Occidental Schism
In 1510, the philosopher James of Athelhampton wrote a text "About the divine right of the king", propagating that the king should stand higher than the bishops in his lands. This basically meant a breakaway from the pope in Avignon. Since he had abandoned Rome, many Christians had criticized him; and since more and more money from the Quadruple Monarchy's lands in Africa and Atlantis went into his coffers, the number of critics had grown even more.
The English nobles accepted the proposal after a few months, but Castille-Portugal was more reluctant to accept the king as head of church. The coalitions formed didn't ask for nationalities, classes, or even families. From 1511-17, the Iberian peninsula went through almost Civil War-like conditions. Finally, the king succeeded. The opponents of the king were rewarded with the property of his defeated enemies (including some church property), which helps him to succeed. He founded the "Occidental Christian church". In 1519, after a meeting of the cardinals of the Quadruple Monarchy, they accepted king Edward as supreme spiritual authority. The liturgy or anything else substantial wasn't changed. The Occidental Schism began. The church property in the Quadruple Monarchy went to the king as well, who used it to give it to his followers, thus further strengthening his authority. When the pope protested, the king declared in return that he wouldn't accept the authority of "the lackey of the French king".
During the 1520s, as a reaction to Edward's Caesaropapism, a new Christian movement spread through Great Britain - the "Independents" who demanded that the state should completely stop interfering with the church, and again demanded the translation of the bible, which the church still declined.
Both king Charles VIII of France and his uncle, the regent François (also Roman king Franz I) felt threatened by the new superpower. When in 1522 Prince Alasdair came to the court and warned the king that the Quadruple Monarchy was about to conquer the rich lands of the Tenochca, the war was declared. 1523-47, the Quadruple Monarchy fought against France, Aragon, the HRE and Mexico.
In the peace of Barcelona 1547, the Quadruple Monarchy had to cede Murcia to Aragon, and accept the independence of Scotland-Ireland under Alexander / Alasdair IV in Europe, and of the Mexica and Inca people in Atlantis. Plus, they had to pay several tons of gold. This lead to the double revolt in 1549 in the (now) Triple Monarchy of England-Castille-Portugal: Both the parliament in England and the Cortes in Castille forced the king to resign, and made his more popular son Edward VI king, who would also start the council of Ghent to reconcile the church. Edward retreated into private life and died in 1554.
Under his successors, the countries were rebuilt and the empire enlarged.
Henry IV led the second Occidental-Seljuk War, acquiring the Marches, Algiers, Tunis and Sicily 1565 in the Peace of Ostia. He also reordered his kingdoms, and had South Atlantis explored, where he founded the colonies of Braseal and Argentine.
His successor Henry V brought the Triple Monarchy to its peak. He made peace with the French king François III, to divide the crown of Aragon and lead the Great Seljuk War together with him, which gave him all of Algeria and Tunisia in the peace of Naples. He also was accepted as king of Ireland and Poland.
Thanks to a row of exceptional rulers, the Triple Monarchy of England-Castille-Portugal survived many decades and could even expand its power by acquiring colonies in Atlantis. But under king Henry VI, it fell apart too. In 1633, uprisings against the unpopular king Henry VI started, which marked the begin of the first English Civil War. (It was also called by the common people "War of the 'fords", after the leaders of the most important groups, the Staffords and the Cliffords.)
1634, king Henry was captured and banned to Atlantis (i.e. he was put onto a ship which captain was told he had a prisoner to be released in Atlantis. Like the nobles used to joke, this was the worst imaginable punishment for the king, who banned that many religious dissenters there.) However, since the king had no heir, the nobles weren't in unison about what to do, and started to fight amongst each other.
During 1642-45, "the Scottish Interlude" happened: Scotland tried to expand into Northern England, which made the Staffords and the Cliffords actually stop their war against each other in 1643, until the Scots were finally driven out.
Rebuilding the Empire
In 1655, Wales became an integral part of England. The Welsh language was suppressed. (This happened about one century later than OTL, since the English kings were preoccupied with the rest of their empire. Now, under the Staffords, they cared more about the islands.)
1662, England reconquered the Pale in Ireland.
The king also rebuilt the empire in Atlantis. After having accepted the loyalty of Markland, he planned to regain England's old colony in North Atlantis. However, the states of Denmark-Braunschweig and Florence allied against him in the "Atlantean Coalition" and surprisingly defeated the English fleet in the war 1652-56. New England thus stayed a Danish-German protectorate.
In South Atlantis, he was more successful. 1657, Sweden agreed to give back Braseal to England, in exchange for an alliance. In the following decades, the English would (re-)found many cities there, like Stafford City, Fort Humphrey and Paradise.
In 1681, king François IV died, which meant that a new Holy Roman Emperor had to be elected. There were also talks to elect the English crown prince, or Humphrey I himself, but both of them died in short time. At the end, king Francisco II of Sicily was elected emperor Franz IV. François V wouldn't accept his defeat, and the anti-French War broke out. English troops invaded Scotland, and also were brought to the Netherlands.
In July 1684, after the Battle of the Lowlands, Glasgow and Edinburgh were besieged by the English army. And in Atlantis, they also were victorious, winning the Battle of Kingsburgh (OTL Montreal) in November 1687. The French-Atlantean troops had to cease the siege and retreat to French Quebec (OTL Ontario).
1693, King Humphrey II died surprisingly. The new English king was just ten years old. In France, advisors told the new king François VI that he should continue the war, since the tide could turn again. (It wouldn't.) Shortly after, the war was won, and in the peace of Amsterdam, England received Quebec, thus expanding its colony Markland nicely to the west, plus the Danish colony Haraldsland, and was allowed to annex Scotland.
After the war, with France humiliated, Britain (as the new state was now called) expanded further. 1704, English ships went west from Cape Hoorn, (re-)discovered Australia and New Zealand, which were called Antipodia and New Albion respectively. England took claim of these lands, but for quite some while they stayed in the shadow of the English colonies in North and South Atlantis.
1716-18, Britain made further discoveries in the Pacific Ocean, where it claimed many islands. As a surprise came the rediscovery of the island Tahiti, where they found a Christian, mostly English-descended population who believed that the Plantagenet dynasty still reigned in the Triple Monarchy of England-Castille-Portugal.
During 1718-23, Ireland was conquered by England. The years of 1727-30 saw some Irish and Scottish uprisings, which were defeated by Britain, however.
In Atlantis, where they had united Markland and Quebec to form Canada, during 1746-50 the French-Atlantean War (also called War of the Great Lakes) was fought. Denmark-Braunschweig and Britain defeated the native Atlanteans and the French immigrants in Quebec.
Meanwhile, France had gone through a succession crisis after the death of Charles X. In 1763, the republic was declared, and 1764-67, it went through the second French Civil War, which the Republicans won.
Now, after the death of the more cool-headed kings Humphrey III and IV of Britain and Héctor II of Spain, who had been self-assured enough not to be impressed by the king-less situation of France, diplomatic tensions to France rapidly worsened. The first French Republican War began. Savoy, the Netherlands, even Hungary under hesitating Charles / Károly VI and many German states joined the coalition; only Italy stays neutral. After initial successes, it ended in a shocking defeat for the monarchists.
The second and third French Republican War weren't more successful either. At the end, all of Britain's allies on the continent were defeated; Sweden had become a French friend, and Germany, the Netherlands, Iberia and Bohemia were French satellite republics now.
The end of the monarchy
Even after these defeats, Humphrey V and his supporters weren't going to give up. In Iberia, they supported continued uprisings of the natives, which bound France in the costly "Ninety-Year War" - and also wasted the money Britain earned at that time in southeast Asia. In Britain proper, Republicans and their possible sympathizers were banned to the colonies.
The resistance thus came first from Canada, which was influenced by nearby German Atlantis which had gone republican a few decades earlier. In 1813, the Canadian Revolutionary War began, for the Canadians felt that they had to pay too many taxes for the never-ending, unsuccessful wars in Europe and were suppressed too. In 1822, Canada could win independence; only Haraldsland stayed British. Probably only the death of Humphrey V in 1825 prevented a revolution at that time.
His son Philip promised to cut back the spendings for uprisings in Iberia, since the events in Germany proved that France's power was already in decline. However, he still managed to anger off possible friends, for symbolical reasons only. Thanks to the Stafford dynasty making strategic marriages to the disposed princes of Europe, his father already had had the majority of the German electors and could thus claim himself to be the rightful Holy Roman Emperor, although the HRE had already ceased to exist at that time. King Philip now renewed the claim. While the Germans didn't care much, it still lead to a conflict when in 1830, after the death of Adolf Ignaz II of Nassau, the people there chose to unite with Germany, while king Philip had a claim for Nassau too.
Even worse, he managed to anger off the emperor of New Rome, Alessandro I. The latter formed a coalition with the Germanies and Canada. In 1832, the Anti-British War broke out. Unexpectedly, the Imperial Navy proved to be stronger than the Royal Navy, thanks to the numerous fights against the Spanish Navy-in-exile. In the peace of Roma Nuova, Britain had to cede Haraldsland to Canada and its lands in South Atlantis, which were divided along the Tropic of Capricorn: Braseal went to New Rome, the Germans received Argentine as a place for settlement (from now on, more often called Argentinien). Patagonia, being uninteresting for the victors, became independent Aymaria.
This defeat was the last straw. In 1838, the English revolution happened. King Philip was killed, the Revolutionaries declared the British republic. The Royal family under his successor George I fled to New Albion (OTL New Zealand). The pope went with them.