At the outbreak of the Second World War, due to the provisions of the "Defence Act (1903)" which precluded sending the Militia outside of Australian territory to fight, it was decided to raise an all volunteer force for overseas service. This force was known as the Second Australian Imperial Force (2nd AIF). The infantry units of the 2nd AIF adopted the same designations as those of the 1st AIF, with the prefix numeral '2' in front to differentiate them from the Militia battalions that continued to exist. As result, during the war there were two battalions to bare the numerals 11th Battalion. The &lt;a href="2/11th%20Battalion%20%28Australia%29"&gt;2/11th Battalion&lt;/a&gt; was attached to the 6th Division and served in the Western Sahara, Greece, Crete and the Tobruk, as well as in the Pacific. At the same time, the Militia 11th Battalion (City of Perth Regiment) was attached to the 13th Brigade, 4th Division and spent most of its active service on garrison duties in Australia before taking part in the New Britain campaign in 1944–45.