Since 1450: The invention of the caravel in Portugal further helps developing oversea trade and colonization.
After the improvements in the first half of the century, the church gradually becomes more corrupt. The riches the Castillians took in Morocco already increased their wishes, and when their share from Atlantis and Africa is rolling in, they're demanding even more.
1453: Since the princes of North and South Portugal can't agree who should reign, Castille can impose its rule again - although the king again has to swear to accept Portuguese rights.
1455: King Louis XII of France has 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's talked by his advisors into it) who are already concerned with the growing power of the king, use this accident to rebel against him.
The ambitious duke Bernhard I of Braunschweig-Lüneburg, who inherited most lands of the Welfs, founds a colony in Atlantis at the site of Philadelphia, called Martinsburg (with the help of the Hanseatic League cities Hamburg and Bremen).
1461: Portuguese discoverers reach the Senegal river. King Pedro IV insists that they try to find a way from here to the gold-rich Mali, which doesn't work. However, they start to trade for gold (and slaves) at the Mauretanian island of Arguim.
1463/64: England defeats Scotland, takes their colony of New Scotland, which is renamed New England, of course. The capital of the colony, Perth beyond the Ocean, is renamed after the winner of the battle, Boston. England slowly extends its settlements, until they go from OTL Bar Harbor, Maine, to New Haven, Connecticut.
1468: First Florentine caravel crosses the Atlantic, finds the way to Nystad. They discover the Potomac, and since the area is yet unclaimed by Sweden, they claim it for Florence.
1469: Brittany sends a ship to the new world; they find the coast of OTL Carolina, but the stronger Dutch don't allow them to make landfall.
1471: Anders Christensen discovers the mouth of St Lawrence river, but is killed a bit later by Atlanteans, so the expedition decides to return.
1475: Another Danish expedition reaches Lake Ontario. Soon, the first Danish colonies along St Lawrence river are founded. Together with the colonies of Prince-Harald-Island and Anderland, they form a belt around English colonies.
1479/80: Sweden makes war with Norway, occupies and annexes Norwegian province of Jämtland.
1481: Tlacaelel, Cihuacoatl ("Prime Minister") of the Tenochca, dies.
Portuguese discoverers go further south, come to Guinea. The income of the Portuguese crown doubles within short time; the money is divided in three between the two Portuguese princes and the Castillian king, however.
1486: France sends the first ships to Atlantis, under a captain Coulon (of the infamous pirate family), making claim in the area of OTL Carolina, where they found Charlesbourg at the site of OTL Charleston.
1488: Portuguese reach the mouth of Niger river.
1490: Charles VI of France makes the Republic of Venice appoint his cousin Jean "protector of the republic", essentially giving him lots of real power, promising them an "everlasting alliance" with France against the Muslims.
1492 (SCNR): A Castillian expedition (well, it's funded by the king, and some of his people are on the ship, but since the Portuguese insisted, the captain and all the sailors are Portuguese - Castillians aren't allowed to build caravels) crosses the Atlantic, makes landfall in Florida (which is named the same way ITTL), claim it for Castille-Portugal.
1493: Huayna Capac becomes ruler of the Incas.
|Earlier in time:|
Western Europe / Atlantis 1400-1450
|Western Europe / Atlantis
|Later in time:|
Western Europe 1500-1550