 From 1930 the battalion was linked with the 1st Battalion to form the 1st/19th Battalion (City of Sydney's Own Regiment), before being linked with the 20th Battalion.During World War II the battalion initially served in the defence of Darwin before being delinked from the 20th Battalion in 1941 and deployed in New Guinea and New Britain.In 1945, the battalion was disbanded and was not reformed until 1966 when it was re-raised as part of the Citizens Military Force, serving as a special conditions battalion known as the 19th Battalion, Royal New South Wales Regiment.