Was the invasion of Poland in WWII a walk in the park like Austria and Czechoslovakia were?

The invasion
of Poland was not difficult for the German army.  However, it was not as easy as the German
occupations of Austria and Czechoslovakia.

The Germans did not actually have
to invade either Austria or Czechoslovakia in any serious way.  In the case of Austria, there
was no military component.  In Austria, there was an internal coup detat in March of 1938.  This
was carried out by the Austrian Nazi...