What are the reasons Prime Minister Menzies gave for Australians going to war?

Prime Minister Robert Menzies was a strong monarchist, staunchly supportive of England. When Great Britain declared war on Germany, Menzies followed by declaring Australia's support. He made the announcement that "in consequence of a persistence by Germany in her invasion of Poland, Great Britain has declared war upon her and that, as a result, Australia is also at war."