John Hays Hammond was an American mining engineer, diplomat, and philanthropist. He amassed a sizable fortune before the age of 40. An early advocate of deep mining, Hammond was given complete charge of Cecil Rhodes' mines in South Africa and made each undertaking a financial success. He was a main force planning and executing the Jameson Raid in 1895. It was a fiasco and Hammond, along with the other leaders of the Johannesburg Reform Committee, was arrested and sentenced to death. The Reform Committee leaders were released after paying large fines, but like many of the leaders, Hammond escaped Africa for good. He returned to the United States, became a close friend of President William Howard Taft, and was appointed a special ambassador. At the same time, he continued to develop mines in Mexico and California and, in 1923, he made another fortune while drilling for oil with the Burnham Exploration Company.

The Jameson Raid was a botched raid against the South African Republic carried out by British colonial administrator Leander Starr Jameson, under the employment of Cecil Rhodes. It involved 500 British South Africa Company police launched from Rhodesia over the New Year weekend of 1895–96. Paul Kruger, for whom Rhodes had great personal hatred, was president of the South African Republic at the time. The raid was intended to trigger an uprising by the primarily British expatriate workers in the Transvaal but it failed. The workers were referred to as The Johannesburg Conspirators. They were expected to recruit an army and prepare for an insurrection; however, the raid was ineffective, and no uprising took place. The results included embarrassment of the British government; the replacement of Cecil Rhodes as prime minister of the Cape Colony; and the strengthening of Boer dominance of the Transvaal and its gold mines. Also, the withdrawal of so many fighting men left Rhodesia vulnerable, one factor that led just a couple of months later to the Second Matabele War. The raid was a contributory cause of the Second Boer War.