sentences:  Hitler and Nazi Germany began to threaten Czechoslovakia in the 1930s.Mucha began work on a new series, a triptych depicting the Age of Reason, the Age of Wisdom and the Age of Love, which he worked on from 1936 to 1938, but never completed.On 15 March 1939, the German army paraded through Prague, and Hitler, at Prague castle, declared lands of the former Czechoslovakia to be part of the Greater German Reich as the Protectorate of Bohemia and Moravia.