On 5 December 1854, Macarthur travelled with the commander-in-chief of British forces in Australia, Major-General Sir Robert Nickle, to the site of the Eureka Rebellion. There they talked with the miners openly and, as a result of their investigations, Nickle advised the withdrawal of martial law. Macarthur was appointed commander-in-chief of British forces in Australia in 1855, to replace Nickle. On 1 January 1856, after the death of Governor of Victoria, Sir Charles Hotham, Macarthur was administrator of the colony of Victoria for 12 months.