Complex sentence: With the exception of the Second World War 1939-1945, the area remained a part of France, and the administration strongly discouraged German language and culture over French, which became the administrative language, and the only language in schools.
Split into simpler sentences: With the exception of the Second World War 1939-1945, the area remained a part of France, and the administration strongly discouraged German language and culture over French. It became the administrative language, and the only language in schools.