▁Part s ▁of ▁West phal ia ▁came ▁under ▁Brandenburg - Pr uss ian ▁control ▁during ▁the ▁ 1 7 th ▁and ▁ 1 8 th ▁centuries , ▁but ▁most ▁of ▁it ▁remained ▁divided ▁duch ies ▁and ▁other ▁fe ud al ▁areas ▁of ▁power . ▁The ▁Peace ▁of ▁West phal ia ▁of ▁ 1 6 4 8 , ▁signed ▁in ▁Mün ster ▁and ▁Os nab r ück , ▁ended ▁the ▁Th irty ▁Years ' ▁War . ▁The ▁concept ▁of ▁nation - state ▁so vere ig nt y ▁resulting ▁from ▁the ▁treat y ▁became ▁known ▁as ▁" West phal ian ▁so vere ig nt y ". ▁ ▁As ▁a ▁result ▁of ▁the ▁Protest ant ▁Re formation , ▁there ▁is ▁no ▁dominant ▁religion ▁in ▁West phal ia . ▁Roman ▁Catholic ism ▁and ▁Luther an ism ▁are ▁on ▁relatively ▁equal ▁foot ing . ▁Luther an ism ▁is ▁strong ▁in ▁the ▁eastern ▁and ▁northern ▁parts ▁with ▁numerous ▁free ▁churches . ▁Mün ster ▁and ▁especially ▁P ader born ▁are ▁thought ▁of ▁as ▁Catholic . ▁Os nab r ück ▁is ▁divided ▁almost ▁equally ▁between ▁Catholic ism ▁and ▁Protest ant ism . ▁ ▁After ▁the ▁defeat ▁of ▁the ▁Pr uss ian ▁Army ▁at ▁the ▁Battle ▁of ▁J ena - A uer sted t , ▁the ▁Tre aty ▁of ▁T ils it ▁in ▁ 1 8 0 7 ▁made ▁the ▁West phal ian ▁territ ories ▁part ▁of ▁the ▁Kingdom ▁of ▁West phal ia ▁from ▁ 1 8 0 7 ▁to ▁ 1 8 1 3 . ▁It ▁was ▁founded ▁by ▁Napoleon ▁and