After the 1913 election, Cook offered Deakin the position of chairman of the Interstate Commission, but he declined. In 1914, following the outbreak of World War I, he did accept a request to chair a royal commission into food supply during the war. Deakin's final public engagement was as leader of the Australian delegation to the 1915 Panama–Pacific International Exposition in San Francisco. He was offered the role initially by Cook and then by Andrew Fisher, who returned as prime minister in September 1914. The appointment was entirely ceremonial and had the support of both Fisher and his deputy Billy Hughes. However, Deakin's involvement was subject to political interference from external affairs minister Hugh Mahon, and he decided on an early return to Australia.