This is the beginning of a 17-minute speech by the Australian Prime Minister Robert Menzies, in which the Australian government, as one of the British Dominions, declares war on Germany in 1939.
The entire speech can be heard and read on the Australian Screen Online website. It’s an amazing resource of Australian audio and video.
You can find out more about R.G. Menzies at MenziesVirtualMuseum.org.