nine children of Patrick Hill "Pat" Osborne (1832–1902) and Elizabeth Jane "Jeanie" Osborne (1847–1938), née Atkinson was born on 14 May 1878 in Sydney. He attended Rugby School from 1892 to 1894. Soldier In early 1898, Osborne was appointed second lieutenant, in command of the Bungendore troop of the First Australian (Volunteer) Horse Regiment; and, a year later, "was proving [himself to be] not only a smart officer, but a very popular one with the men". In October 1899, he was one of two members of the New South Wales military forces to be briefly appointed honorary aides-de-camp to the staff of Earl Beauchamp, the Governor of New South Wales,The Defence Force, The (Sydney) Evening News, (Monday, 30 October 1899), p.7. who was also Honorary Colonel-in-Chief of the First Australian Horse Regiment. He commanded the first troop of the 1st Australian Horse service squadron to be sent to South Africa. Lieutenant Osborne sailed with his troops for South Africa on the S.S. Langton Grange, leaving Newcastle on 15 November 1899, arriving in South Africa, at Durban, on 13 December 1899. He was present at the Relief of Kimberley and, in March 1900, left the Australian Horse and took up a commission with the British 16th Lancers: the regiment of his elder brother, Second Lieutenant Edwin Francis Fitzroy Osborne (1873-1895), who had died four years earlier, of enteric fever, at Lucknow, on 2 September 1895. He was closely involved in the surrender of Bloemfontein in March 1900; and, in early May 1900, he contracted enteric fever. He was hospitalized in Bloemfontein; however, his condition did not respond to treatment, and he was invalided to England. Having participated in operations in the Orange Free State and Transvaal, and having seen action at Reit River, Klip Drift, Relief of Kimberley, Paardeberg, Poplar Grove, Dreifontein, Karee Siding, Belfast and Slingersfontein, Osborne was awarded the Queen's South Africa Medal with five clasps. His service is commemorated on a plaque (dedicated on 29 May 2011) affixed to the Bungendore and District War Memorial. He remained on the "unattached list" until he formally resigned his commission in December 1904. Aide-de-camp to Earl Ranfurly In 1901, appointed to the rank of captain, he served as the aide-de-camp to Earl Ranfurly, the Governor-General of New Zealand, in particular, during the visit of the Duke and Duchess of Cornwall and York (later, King George V and Queen Mary) in June