The Frisia region was largely independent of the Holy Roman Empire's authority, without the rest of the region's feudalistic structures. The independent chieftains of Frisia formed the Upstalsboom in the twelfth century, as an alliance against German intrusion, and consisted of modern Friesland, Groningen, East Frisia, Harlingerland, Jever and Rüstringen. The league would also occasionally attract the districts of West Friesland, the districts north of the Eider River (Schlesqig-Holstein), and many Dutch polities. By the late fifteenth century the Frisians came under attack by their neighbors, with many noblemen often attempting to claim the title of Count of East Frisia. The most successful of which would be Albert III, Duke of Saxony, who managed to secure a loose hold over Frisia just before his death in 1500.
One of the leading forces against the Saxon duke was Pier Gerlofs Donia, a pirate lord and local folk hero. The region was terrorized by the Black Band, a Landsknecht regiment in the service of the Saxons, which angered the locals. With aid from Charles of Egmond, Duke of Guelders, and other lords angered by the marauding mercenaries, Donia organized a rebellion against them and begin a guerrilla war campaign. At sea Donia's pirate fleet was highly successful, raiding the Zuider Zee and gaining the ire of everyone from enemy lords to the writer Erasmus. Donia would eventually be elected as a leading figure of the Upstalsboom in 1525, after the Saxons agreed to withdraw. By this time war had broken out elsewhere in Germany, and the Protestant Reformation was beginning.
After the German Peasants' War in southern Germany, the Anabaptist movement began to spread to other sections of central Europe. Melchior Hoffman is credited with the introduction of Anabaptist ideas into the Low Countries. Hoffman had picked up Lutheran and Reformed ideas, but on 23 April 1527 he was "re-baptized" at Strasbourg, and within two months had gone to Emden and baptized about 300 persons. After narrowly evading capture in Strasbourg in the following years, he traveled into the Lowlands, baptizing and preaching to as many people as possible. Hoffman's teachings inspired other influential preachers, such as Bernhard Rothmann. Bernhard Rothmann was a tireless and vitriolic opponent of Catholicism and a writer of pamphlets that were published by his ally and wealthy wool merchant Bernhard Knipperdolling.
The pamphlets at first denounced Catholicism from a radical Lutheran perspective, but soon started to proclaim that the Bible called for the absolute equality of man in all matters including the distribution of wealth. The pamphlets, which were distributed throughout northern Germany, successfully called upon the poor of the region to join the citizens of major cities, to share the wealth of the towns and benefit spiritually from being the elect of Heaven. These teachings quickly caught on in the Frisia region, where resistance was already occurring against religious and political authorities.
The Anabaptists flooded to cities such as Groningen, the de facto capital of the Frisian league, where they were able to easily overtake the existing aristocracy in its council elections. Bernhard Knipperdolling was appointed mayor of the city, with the last of the Catholic leaders, and many Lutherans as well who were deemed hostile to the movement, exiled from the city. A period of rapid re-baptism spread across Frisia, with peasants also being attracted from Holland and parts of northwest Germany. Hoffman's teachings became increasingly apocalyptic and visionary, with him making many prophecies on the second coming of Christ. He is said to have received visions of "resurrections" of apostolic Christianity, first under John Hus, and now under himself.
As predicted, many of the region's neighbors took up arms against the Frisians or the peasants they inspired, with major clashes occurring in Oldenburg and Holland. Hoffman began to call for a great migration, first to inner Frisia, hoping to amass as many soldiers as possible to defend the movement in a concentrated place. At the same time, another group headed south to preempt any invasion, by seizing the city of Münster. The group was led by Jan Matthys (also spelled Matthijs, Mathijsz, Matthyssen, Mathyszoon), a baker from Haarlem, and Jan Bockelson (or Beukelszoon), a tailor from Leiden. They took over the city through election, in a manner similar to Groningen, before ousting the previous leaders of the city. They then began compulsory baptizing, led an iconoclastic plundering of the city's cathedrals and monasteries, and redistributed the city's wealth to poor Anabaptist peasants. Later it would be proclaimed that all property in the city was to be held in common.
By that time thousands had migrated north to Frisia, while thousands more had poured into the religious fortress of Münster. The leaders of the city justified their authority and actions through visions from heaven, and they adopted the regalia of royalty by claiming descent from the line of David. The city's leadership had also legalized polygamy in order to address the city's uneven demographics, with Jan Bockelson marrying sixteen women. The Münster regime came under attack in April 1535 from many surrounding lords, including Franz von Waldeck, the exiled bishop of Münster, despite attempts to negotiate from the primary Frisian government. After a year long siege, which resulted in both the deaths of Jan Bockelson and Jan Matthys, the city was eventually captured.
The survivors of Münster became led by Jan van Batenburg, who continued policies of polygamy and fierce warfare, but they became less favored in the eyes of other Anabaptist leaders. Seeking to deter an invasion of Frisia, the Münster leaders were publicly condemned by their allies in the north. Nevertheless, peace did not seem likely, and Hoffman continued to advocate for a great migration to a new promised land. In the Spanish Netherlands the work of Diogo Ribeiro and other cartographers became known among elites, following Charles I's commissioning of Estevão Gomes and other explorers to the New World in the west. Many merchants in the Lowlands became intrigued by the economic prospects of the fabled rich west, while also seeking to settle the issue of the Frisian revolutionaries.
In 1539 an expedition was launched from of three ships was launched from Holland, carrying 210 Anabaptists and 85 other sailors, under the command of Obbe Philips. They traveled west through the English channel and followed a similar route that the English explorer John Cabot had followed decades earlier. Although intending to land in the lands described by Cabot and other explorers, they were blown off course by a storm. Instead they landed northeast of the charted Hudson River, near the OTL Block Island Sound. After coming across a small island (OTL Fishers Island), they turned north and found a small river (OTL Pawcatuck River). Here they began construction of a settlement, but they had suffered many losses while in transit to the region. By the following spring only 170 people remained, with many succumbing to disease and the harsh winter that year.
In 1540 Philips departed with a ship back to Frisia, bringing news of the settlement. His arrival sparked interest in a major expedition, and this time Pier Gerlofs Donia would personally lead his immense fleet west with as many zealots as were willing to accompany him. Despite petitions that he should remain in Frisia, Melchior Hoffman also would accompany the voyage, after prophesizing that he would not die in Europe. Instead Frisia was left in the hands of a small council, consisting of Obbe's brother Dirk Philips, David Joris, Claus Frey, and other theologians. Obbe Philips departed first with a single ship, arriving at the settlement that summer. He brought a small number of men to the settlement, as well as much needed supplies. He would spend the rest of the year sailing around the region, attempting to scout the surrounding area. He would eventually discover the future locations for many of the colony's major cities. At the end of the year the Donia fleet arrived with 1,500 people, and they were directed to a location discovered by Philips.
Although many chose to settle in the previously established colony, Hoffman led the majority of settlers up the "Fresh River", arriving at a point several miles inland. Scouts had previously trekked across the region, and a small contingent of soldiers had established Fort Goede Hoop after buying the land from the local Pequot natives. Hoffman's group arrived at the fort and began construction of a settlement adjacent to the fort, which he named Moriah. Likening himself to the biblical king Solomon, Hoffman hoped to build a great temple in the center of the city, but he would not live to see such a project's completion. Pier Gerlofs Donia would become an explorer for much of the year, traveling as far south as OTL New Jersey, and as far north as OTL Boston. These areas were not sanctioned by Hoffman, as he believed their current location was the prophecized location of the promised land. After disagreeing with some of the practices of the more zealous leaders, Donia would lead a small group to settle an outpost between the two settlements, known as Pierswerd (OTL New London).
News of the successful colony attracted attention from much of northern Europe, with as many as 20,000 people migrating to the colony within the first two decades. Primarily these colonists were Anabaptists or Frisians, but the Dutch, German religious dissenters, and the English also formed sizable minorities in the colony. Melchior Hoffman served as the de facto religious and political leader of the colony, but in practice each community was highly autonomous and decentralized. Frisia became increasingly divided politically, as differing members of the Anabaptist movement began to disagree on religious practices. After David Joris won out among the council, as a proponent of a moderate and peaceful path with the rest of Europe, one of the most radical members of the council, Jan van Batenburg, resigned and headed for the New World.
Known as the Batenburgers, this group quickly settled and overtook the entrance to Moriah, making themselves important to the other contingents. With Hoffman's unexpected death in 1543, a scramble began to assert leadership over the entirety of the colony. A council was called in Moriah, where the laws of the colony were codified, based on Frisian principles. Each settlement remained free and autonomous, but would send representatives to Moriah to form a council representing them all as one. Batenburg's presence helped to ensure that polygamy would not be outlawed, while other groups chose not to practice it. Batenburg would also carry out a policy of mass baptism and warfare against the natives, while most other communities peacefully coexisted with the natives for the time being.
Other regions soon followed the Frisians, establishing non-Anabaptist outposts in the New World. The house of Cirksena under Edzard II, a Lutheran Frisian, would sponsor an expedition to the region in 1545. Many Dutch cities also sponsored expeditions to the region, hoping to trade with the new colony and nearby natives. The Hanseatic League, who were rivals of the Frisians and attempting to reverse their rapid decline, sponsored an expedition to the region in 1550, founding the colony of New Haven to the west of the Anabaptists. Originally founded as an outpost for trading with the natives, the colony attracted many Dutch and German settlers.
In Europe another sect of the Anabaptist movement emerged, led by Menno Simons, known as the Mennonites. This group would quickly become a major power in Frisia with its own philosophy. While Joris and other mainline Anabaptists placed more emphasis on "spirit and prophecy", Menno emphasized the authority of the Bible. For the Mennonite side, the emphasis on the "inner" and "spiritual" permitted compromise to "escape persecution", while to the Joris side, the Mennonites were under the "dead letter of the Scripture". With Frisia primarily siding with Joris, Menno preached often in northwest Germany. Due to the memory of the war at Münster, the Anabaptists faced persecution in the region, leading to many Mennonites joining their brethren in the New World.