Following the outbreak of World War I, the Australian Naval and Military Expeditionary Force (AN&MEF) occupied Bougainville in December 1914, as part of the broader Australian occupation of German New Guinea. The 1919 Treaty of Versailles established the former German territory as a League of Nations mandate, the responsibility for which was awarded to Australia. The Australian military administration had adopted a "business as usual" approach and secured the support of the existing German business community. It was replaced by a civil administration in 1920, which expropriated the property of German nationals without compensation and deported them.