Frisian
Frisian is a group of West Germanic varieties spoken along the southern shore of the North Sea; together with English and Scots it forms the Anglo-Frisian branch. Old Frisian was remarkably close to Old English and survives mostly in legal texts.
In the fourteenth century the Frisian lands enjoyed the so-called Frisian freedom: rural communes without feudal lords elected their own judges and fought repeated wars against the counts of Holland. That autonomy ended when the County of East Frisia was formed in 1464 and Saxon troops occupied western Frisia in 1498, after which Dutch replaced Frisian in government, law and the church.
The poet Gysbert Japiks revived Frisian as a literary medium, and a broader revival around 1820, led by scholars such as Joost Halbertsma, produced a modern written standard.