This is a page to list the major differences between OTL and the TATM ATL. It will also explain how the POD led to the modern day, and various events between.
This explanation has been organized according to the butterfly effect. The divergence quickly spreads through the world, but this will only deal with the portions that have already changed due to that. For instance, the first 5 years (in the Point of Divergence section) will only cover England and France - but will then spread onwards.
A Note on the Situation in Europe, before the POD
Following the fall of the Roman Empire, until roughly the First Crusade, Europe was split between the Germanic North and the Romantic South.
In many ways, the so called "Dark Ages" applied only to the Romantics. It was during these "Dark Ages", for instance, that the Angles and the Saxons unified England (which came from the word "Angle land", or "Angland"- I mainly use the latter in this TL), that Charlemagne founded the Frankish Empire, that Scandinavia was at its height, that Russia experienced its Kievan Golden Age. Meanwhile, the Romantics were constantly warring with each other, with the Germanics to the North and the Muslims to the South.
By 1066, the grounds between the two were more even - the French were now by and large Romantics, though extremely divided ones. In fact, it was the years between 1066 and 1095 (the First Crusade) that determined the end of this struggle. The Romantics had, insofar as a cultural victory can be established, won- as manifested by the Pope's control over most of the nations of Europe.
There are two main events behind this - firstly, of course, the Battle of Hastings and the Investiture Controversy. As the earlier of these was the Battle of Hastings, the POD is there- but the Investiture Controversy will play a big part too.
Point of Divergence
The POD for this TL is that King Harold Godwinsson of England defeats William of Normandy at Hastings, in 1066 (in this case, the arrow, which, in OTL, first caused Harold to fall, missed, letting him survive and rally his troops - hence the title).
Following a string of defeats, Harold kills William, and then spends five years consolidating his kingdom, while the Normans fight huge wars over the successors to William, which draw in the neighboring regions. Eventually, Harold sees an opportunity to stake a claim over Normandy, and invades. After nearly five years of fighting, he manages to militarily control much of Northern France, including Normandy, Calais, Maine, Anjou, and Brittany. Because the French were unable to form a united front, he was easily able to keep these territories and install his own trusted men over them - his brother Leofyne, for instance, was granted control over Normandy. His son and successor, Edmund III (The Hammer), would briefly rule over the City of Calais before his father's death.
Extremely Short Term (1075-1100)
At the same time as the fall of France, the Pope and the Holy Roman Empire were clashing (also in OTL) over the Imperial appointments to clerical positions. This was known as the Investiture Controversy. In addition to this clash, however, tensions were suddenly racheted up by the Anglish invasion of France. Since William's original invasion had been supported by the Pope, the Pope thus ordered the HRE to avenge and help the French, as William's attack on England had been supported by the Pope, and was considered one of the first Crusades. This was an unpopular move in the HRE and in the Papal States themselves, which had been threatened by the Norman invasion of South Italy in 1054.
The Emperor refused, and was supported by many of his nobles, who did not wish for war. After a brief and brutal civil war in the HRE, the Emperor (Henry IV) marched on Canossa, sacked it, and forced the Pope to recant his Interdict on Angland and to allow the Emperor to appoint clerical figures within the HRE.
Ironically, this would overall lead to a strengthening of the Church, as in 1086.