With Danish troops within his territory and "Christian the Younger's" request Administrator "John Frederick" tried desperately to keep his Prince-Archbishopric out of the war, being in complete agreement with the Estates and the city of Bremen. When in 1623 the Republic of the Seven United Netherlands, fighting in the Eighty Years' War for its independence against Habsburg's Spanish and imperial forces, requested its Calvinist co-religionist of the city of "Bremen" to join, the city refused, but started to enforce its fortifications.