The Peace of Westphalia ended the Thirty Years' War. The duchies of Liegnitz, Brieg, Wohlau, Oels and the city of Breslau retained religious freedom, and the construction of three Protestant churches, the Churches of Peace, was permitted. The systematic oppression of the Protestant faith was intensified in the rest of Silesia as most churches were closed or given to the few remaining Catholics. A new exodus to surrounding countries started, which led to the foundation of several new towns. Protestant churches close to the Silesian border, the so-called "border churches" (German: Grenzkirchen), were built to provide a place where Silesians could practise their religion.