the great depression triggered WWI
invasion of poland
Hitler's invasion of Poland in 1939.
Germany's invasion of Poland.
The breaking point was when Germany invaded Poland on September 3rd 1939
The incident that triggered the beginning of World War 1 was the assassination of the heir to the Austro-Hungarian throne.
Archduke Ferdinand
The assassination of archduke Ferdinand
German submarine warfare
The assassination of Archduke Franz Ferdinand of Austria, which led to the outbreak of World War I ----
He was killed in Sarajevohttp://en.wikipedia.org/wiki/Archduke_Franz_Ferdinand_of_Austria
June 28, 1914.
Poland, on 1 September 1939
it was the 2nd world war
The war is generally accepted to have begun on 1 September 1939, with the invasion of Poland Slovakia
The shooting of the Archduke of Austro-Hungarian Franz Ferdinand.
The assassination of Archduke Franz Ferdinand of Austria-Hungary by Serbian nationalists.