A small point which might save confusion. You say "...tal when in German control." It would not be "tal" "when in German control", it would still be German if it was spelt "thal". In older German "th" was often used but the sound was just "t" - das Thal = valley, das Tal = valley, Rosenthal, a not uncommon name is pronounced Rosental and sometimes spelt that way. The "th" for the "t" sound is simply something which has died out in modern German, nothing to do with a different language or government.