After 1870, the Poles were under an increasing pressure of Germanisation, and the Kulturkampf attacked their Catholic Church. Most Catholic bishops were imprisoned or exiled. The teaching language which had previously been Polish in the predominantly Polish-speaking areas in Prussia was replaced by German as teaching language, even in religious education where Polish priests were replaced by German teachers. However, these Germanisation policies were not at all successful. In contrast, it led to the political awakening of many Poles and to the establishment of a wealth of Polish economic, political and cultural associations which were aimed at preserving Polish culture and Polish interests, especially in the Province of Posen and in the Ruhr area. The policy of forced cultural Germanisation alienated large parts of the Polish-speaking population against the German authorities and produced nationalistic sentiments on both sides.