 An alternative policy was put forward in 1923 by the Australian Labor Party, which was in opposition for all but two years of the 1920s and 1930s. It called for Australia's first line of defence to be a powerful air arm, supported by a well-equipped Australian Army that could be rapidly expanded to meet an invasion threat. This, in turn, required a strong munitions industry. Labor politicians cited critics like Rear Admiral William Freeland Fullam, who drew attention to the vulnerability of warships to aircraft, naval mines and submarines. The Labor Party's Albert Green noted in 1923 that when a battleship of the day cost £ 7,000,000 while an aircraft cost £ 2,500, there was a genuine cause for concern as to whether the battleship was a better investment than hundreds of aircraft, if the aircraft could sink battleships. The Labor Party's policy became indistinguishable from the Army's position.
