When did hitler invade Rhineland?

Germans have occupied the Rhineland for a considerable length of time! I suspect that the question should be "When did Germany remilitarize the Rhineland?", the answer being 1936.

The Rhineland had been made into a demilitarised zone after the Great War, under the terms of the Treaty of Versailles, 1919. Germany had political control of this area, but was not allowed to put any troops into it. In 1936, Hitler ordered troops to re-enter the Rhineland, thus breaking the terms of the treaty.