[3][4] Soon after Cahill became aware of 60,000 water buffalo in the Alligator River floodplains, near Darwin, and entered into a partnership with William Johnson to shoot them for their hides and horns.
[2] In 1906 Cahill and Johnston settled in Oenpelli (Gunbalanya) where, with the help of Gaagudju people, they established a farm where they grew fruit, vegetables, sisal, cotton and other products.
Cahill planned to employ Aboriginal people to work under 'European' supervision and establish a wide range of experimental crops (including tobacco) and run a cattle and dairy herd.
[11] This venture was, ultimately, a failure due to financial mismanagement and staffing difficulties, however, it was finally ended by the Spanish flu outbreak there in 1919 in which Cahill and Maria both almost died.
[9] Cahill also had major political difficulties at this time due to his friendship with John Anderson Gilruth, for which he was viewed as being on the 'wrong side' of the Darwin rebellion and called before the Ewing Royal Commission.
[2] After the Inquiry, in 1920, Cahill's lease was officially proclaimed an Aboriginal Reserve and, in 1924, after he and his family had left the area it was transferred into the control of the Church Missionary Society and was renamed Oenpelli Mission.