The battalion was disbanded in 1919, but since 1921 has been re-activated and merged several times as a reserve unit, initially as the 11th Battalion (City of Perth Regiment), which fought a brief campaign against the Japanese on New Britain during World War II. Other units that have maintained the traditions of the original 11th Battalion include the 11th/44th Battalion (City of Perth Regiment), 'A' (City of Perth) Company, 1st Battalion, Royal Western Australia Regiment and the current &lt;a href="11th/28th%20Battalion%2C%20Royal%20Western%20Australia%20Regiment"&gt;11th/28th Battalion, Royal Western Australia Regiment&lt;/a&gt;.