The Protestant Movement was organized in Su'yet of LY 902, at what became known as the first Protestant Pilgrimage, when Bishop Therman of Plist and a number of others broke off from The Order. The ultimate result of this was the formation of the second religious organization in the history of The Land, but that was not, in the strictest sense, the original purpose of the break. It was actually done in opposition to The Plan, which was the blueprint for an endeavor known as the Coming of the Order, which had been conceived by Bishop Kizin of Monab. One of the first bishops to join Therman's cause was Toros of Triscot. The Movement was also joined early on by Drag, who was at the time Grand Sorreter. He brought with him many of his fellow Sorreters, the most prominent of them being Lorraine. (The "Protestant Sorreters" became one of the most powerful weapons of the Movement, as well as creating a mystery when they disappeared en masse during the Battle of Triscot in 903.) However, there were many important figures who joined the Protestant Movement, who were neither spirit-talkers nor Sorreters. One influential member of the Movement was Vallus, an adventurer from Kimrin who traveled the world, speaking to crowds in many villages about the underhanded methods the Order was employing in their attempt to establish a world government. Another major opponent of the Plan was Adam of Triscot, on whose estate the Battle of Triscot was fought in 903. Throughout 903, the Protestants raised armies and navies in various villages, knowing the Order had already done likewise, in anticipation of this dissent. But ultimately, the Order had had much longer to prepare, and the Protestant Movement was defeated.
However, just because they lost the war didn't mean there were no more Protestants. The Movement ended, but Protestantism carries on as a second religion, which the Second Order officially recognized as having equal rights to the Order. Any Protestants who survived the war were granted amnesty in 905, and all people are free to worship in any way they choose (including the loose organization of a third denomination, the "Independents"). It should also be noted that when the surname law was passed in 904, many people chose the name "Protestant." In fact, because most surnames are held by individual clans, whereas those named "Protestant" need not be related nor even acquainted with one another, it is actually one of the most common surnames in the world. (Though it's safe to assume that the overwhelming majority of people who consider themselves Protestants in a religious sense don't go by that surname, but rather have their own distinctive family names.)