East Prussia offered a home to many religious refugees, above all to Protestants. In the north "Prussian Lithuania" soon developed and Protestant Poles came to Masuria. But Swiss people, Scots, people from Hesse-Nassau and Dutch Mennonites also made their presence felt. The latter settled in the Memel region and developed the famous "Tilsit cheese". Frederick William I in particular promoted the "repopulation" of East Prussia, where the "Great Plague" of 1709-11 had claimed up to 250,000 victims, more than a third of the entire population. Whole regions had been deserted and depopulated.
Especially spectacular was the migration of the Salzburg Protestants, to whom Frederick had sent a "Patent of Invitation". About 20,000 of them had been expelled, partly in the middle of winter, by their sovereign, the Roman Catholic archbishop Leopold von Firmian. Thousands of families migrated in several treks as far as northern East Prussia. They were welcomed by the king when they passed through Berlin with the words "For me new sons, for you a gentle homeland."
Illustrations:
1.) The migration of the Salzburg Protestants, “For the mountains may collapse and the hills may reel, but my gracious love will not depart from you“, copperplate by Elias Baeck, 1735
From several places of the mountainous Salzburg landscape with the river Salzach, a large crowd wind their way under the blessing of the Mother of God, the Virgin Mary. Words of comfort emanate from her halo. Psalm 32, verse 8 is written in her gloriole which reads: "I will instruct you and teach you in the way you should go..." For the artist the migration to Prussia was under God's umbrella and blessing.
2.) The arrival of the Salzburg Protestants in Königsberg, copperplate around 1735