Cecil John Rhodes (1853-1902), British prime minister of the Cape Colony, plotted with Sir Leander Starr Jameson (1853-1917), British colonial administrator of Mashonaland, to overthrow the Boer government of the Transvaal under President S. J. Paul Kruger (1825-1904). Rhodes, who controlled extensive diamond mines, envisioned a federation of all South Africa under the British flag. On December 29, 1895, Jameson, disregarding Rhodes' request to delay any action, invaded the Transvaal with some 600 mounted men but suffered defeat at Krugersdorp on January 1, 1896, and surrendered the next day. The Boers handed him over to the British, at their request; Jameson was tried and convicted in London and served only several months in prison. Others in the raiding party were eventually released by the Boers in exchange for a large payment.