What kinds of aggressive steps did hitler take in the 1930s? how did european leaders respond? why?

When Hitler came to power he was determined to make Germany a great power again and to dominate Europe. He had set out his ideas in a book called Mein Kampf (My Struggle) that he had written in prison in 1924. His main aims were

To destroy the Treaty of Versailles imposed on Germany after her defeat in World War One.
Hitler felt the Treaty was unfair and most Germans supported this view.To unite all German speakers together in one country.
After World War One there were Germans living in many countries in Europe e.g. Austria, Czechoslovakia, Poland.
Hitler hoped that by uniting them together in one country he would create a powerful Germany or Grossdeutschland.
To expand eastwards into the East (Poland, Russia) to gain land for Germany (Lebensraum- living space).
European leaders were shocked when this outrageous act happened.