Upon the death of Osweald the crown and Republic passed down to Grand Prince Balthere, ruler of Britannia. And with the acquisition of the last Norse and Irish strongholds, all of Britannia. Belthare even managed to kill the Norwegian King in battle over his last British islands. There was some issue with religion and succession though, that had to be sorted out at once. Swithelm, the fourthborn son and second oldest son of Osweald after the death of two of his older siblings by pneumonia and the oldest surviving brother of Balthere.
He also happened to be a Cathar and was made King of Scotland by Osweald, whilst Balthere was Catholic and Grand Prince of England, Wales and Ireland. Osweald had also given the Cathar heresy much religious authority by virtue of its victories over Christendom and the Norse and Cathar bishops infested the British Isles, converting more lords to their cause. King Swithelm had a claim to take the Republic of Britannia and he had the support needed to do so.
He was murdered on the orders of Grand Prince Balthere aged 32 on the year of 906. With no heirs of his own the Kingdom of Scotland passed back to Osweald, his wife died of depression years later.
Much of Grand Prince Balthere's reign over Britannia was limited to Britannia, that is until Balthere's French allies desperately called him for support during a Muslim invasion of France. This is the point during which Balthere saw the threat of Islam and decided to do more for Christendom than fight the Norse infidels. A force of 4,000 Huscarls was left in France for the rapid deployment against Muslim invasions and Balthere continued the training of his elite and highly disciplined Huscarl army, increasing their numbers until Britannia had the second largest army in Europe; numbering only less than the mighty Arabian Empire, the Abbasid. Having to deal with the Norse was enough on Balthere's plate in addition to the remnants of the Cathar, still strong; Balthere would have given up and joined them had the Pope in Rome supported Britannia's fight against the infidels with copious amounts of papal gold.
Balthere would continue to secure Europe from the infidels by taking over a Spanish county from a cruel Lord unfit to rule, and from there waged war no the Umayyad Caliphate. For no reason other than to weaken the Caliphate and render it incapable of invading France a war was declared on them for the sake of one more Spanish county; the war was long, but won on the battle of Segovia when 10,000 Huscarls fought 17,000 Umayyad soldiers and emerged victorious, having lost 2,000 and killed 9,000, pursuing the survivors to destruction. The Umayyad had been humiliated by a smaller country, smaller army and smaller family.
In the East trouble would be brewing however, with the Byzantine Empire beginning to dissolve under Abbasid pressure, civil disorder and chaos. Even the capital of Constaninople would fall, being taken over by the Norse Lord Gnupa the Conqueror. The Papacy in Rome would decide now is the time form Holy Orders and allow the use of Crusades to defend Christendom. Three weeks after creating this power, the Papacy would call the First Crusade on the Abbasid to take Jerusalem.
Now Balthere didn't really care; Jerusalem was a long way away from Britain and all of Christendom was more or less fighting the Abbasid, there was no way they could lose. In addition whilst this was going on Balthere fought a long and grueling war to subjugate Aquitaine to have safe ports and a barrier against Muslim Spain.
When at last Aquitaine was taken Balthere decided to join the First Crusade and see how it was going along. Evidently, poorly.
The First Crusade looked to be an abysmal failure; having not experienced any good to come from Muslim levies however, Balthere was ready to fund an expedition to Jerusalem. 13,000 British Huscarls landed in Jerusalem led by the Marshal, the Duke of Mercia and the Grand Prince himself. The Huscarls quickly went to work, capturing several key cities and reversing the general downward trend of the Crusade. While attacking under the Mount Sinai the 10,000 surviving British Huscarls were attacked by a fast moving force of 29,000 Muslim soldiers. The Huscarls put up a daring fight, the centre and right wings of the Huscarl armies routed 17,000 soldiers with just 7,000 men. The left wing of the Huscarl army fell to the 9,000 men led by the Umayyad Caliph Isa whose men refused to back down, and they ultimately slaughtered the remaining 4,000 Huscarls of the centre and right flank. Balthere managed to escape the total slaughter of his elite army, very angry. 12,700 Huscarls had died and 12,700 Umayyad soldiers had died.
Balthere returned months later with a force of 13,000 levies from all across Britannia and once more attacked Jerusalem, this time certain Britannia would be victorious. They were slaughtered to the man, having killed only 4,000 enemy soldiers.
Balthere was furious. He had emptied Britannia of levies and Huscarls, leaving it completely vulnerable to Viking raids. Towns and trade posts were destroyed and his armies wasted. He mustered all the republic gold he had left, acquired all the Jewish, Templar and Papal gold he could possibly acquire and once more set off for Jerusalem with an army of Holy Knights and mercenaries. Balthere was nearing his 70th birthday and had to win this war lest his legacy be the Grand Prince who failed.
By the time Balthere reached Jerusalem with the 3rd expedition the First Crusade was weeks away from ending in defeat. 17,000 Abbasid soldiers attacked 23,000 Catholic crusaders on the beach of Asqalan, this was the last possible hope for Christendom. The battle ended in a Catholic victory, 4,000 Catholics dead and 13,000 Muslims slain. It had bought the time the Crusade desperately needed.
There were setbacks. The failed second expedition had angered the peasants who started a rebellion in Britain. In addition the mercenaries sent to Jerusalem were angry that Balthere could no longer pay them and tried seizing Aquitaine and England by force as payment. One of the mercenary rebels was run down and slaughtered by the Knights of the Order Hospitaller, but the others were a much larger threat.
By the time the crusade was over Britannia had lands stretching from Iberia, Iceland and Norway to Aquitaine and Jerusalem - Jerusalem awarded to Britannia for all the thousands who sacrificed themselves for the Lord. There was also much civil unrest from the crushed peasant revolts, the cathar heresy still living strong and continuously rebelling, the endless Norse raids, the bankrupt trade republic's economy spawning religious fundamentalist factions, the Abbasid forming Jihads in response to the fall of Jerusalem, the Aquitaine King resenting Balthere and the Italians and Byzantines getting belligerent.
Finally Balthere declared war on the Italian King Raineri the Cruel and the Norwegian King and at the most unfortunate time as during this time the Umayyad declared a Jihad on Jerusalem. Then the Abbasid declared a Jihad on Jerusalem. Then Sunni rebels emerged from Jerusalem declaring independence.
Jerusalem quickly became the battleground between the three largest military forces in the world in addition to the Sunni rebels, everyone hostile to everyone. Shia fought Sunni, Sunni fought Catholic and Catholic fought Shia. It was the first great war in which hundreds of thousands of men died, brutal battles where tens of thousands would fight tens of thousands happening by the month - even after Caliph Isa was slain in battle by Osweald's forces the fighting still went on for years. It saw the employment of all Catholic Holy Orders, the full commitment of every Huscarl in Britannia's army, the employment of every Muslim Holy order and ended in a British victory. The British had managed to hold onto Jerusalem by entrenching themselves in the mountains and had survived the crossfire.
Peace was not long held as before the Jihads ended the Aquitaine league declared independence from Britannia. They plunged half of Europe into war against the other half as the weary defenders of Jerusalem returned home only to have to fight once more. Thousands died but in the wake of the Jerusalem War the European wars paled in comparison. The Kings who rebelled were thrown in the dungeons of Prince Balthere who died at the age of 77 of natural causes.