How far was Hitler's foreign policy to blame for the outbreak of war in 1939?

The Saar:

Since 1919 the Saar region of Germany had been ruled by the League of Nations. In 1935, the League promised to hold a plebiscite for the people to vote whether the region should return to Germany or not. 90% voted to return to Germany which was legal within the terms of the Treaty of Versailles and it was also a real morale booster for Hitler.

Remilitarisation of the Rhineland:

Under the terms of the Treaty of Versailles, there were to be no armed forces in the Rhineland and it had also been accepted in the Locarno Treaties of 1925.

Hitler timed it well…