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.

Sarah was sister to Captain John Coffee Hays of the Texas Rangers, and had formerly been married to Calvin Lea.

After an adventurous boyhood in the American Old West, Hammond went East to attend the Sheffield Scientific School of Yale University, where he earned a Bachelor of Philosophy in 1876, and later attended the Royal School of Mines, Freiberg, Germany, 1876–1879, and there he met his wife-to-be, Natalie Harris.

In 1894, he joined the British South Africa Company to work with Cecil Rhodes and opened mines in the Rand, in Mashonaland (territory which became Rhodesia (now Zimbabwe).

They demanded a stable constitution, a fair franchise law, an independent judiciary, a better educational system, and charged that the Government under President Paul Kruger had made promises, but failed to keep them.

In May it was announced that they would spend 15 years in prison, but by mid-June Kruger commuted the sentences of all, Hammond and the other lesser figures each paying a £2,000 fine.

His report on Winfield Scott Stratton's Independence mine, also in Colorado, and then being floated on the London market, revealed that the ore reserves had been greatly overvalued, and burst the stock bubble.

[3][4] Hammond was also active in the Republican Party and he became a close friend of President William Howard Taft whom he had known since his student days at Yale.

[5] In early 1908 it was announced that Hammond was a candidate for Vice-President for the Republican party, but he did not receive many delegates at the national convention.

In May 1926, an organization called "The Company of Friends of John Hays Hammond" sponsored eleven dinners around the world (Manhattan, San Francisco, London, Paris, Tokyo, Manila, etc.)

Over 10,000 people wrote tributes to Hammond, including: Hearst whose father gave him his first job, Woolf Barnato whose father (Barney Barnato) took him to South Africa, Sir Lionel Phillips who was condemned to death with him, the Guggenheims who employed him at a fabulous salary, former President Taft who offered him an ambassador position, and President Calvin Coolidge who consulted with him on the coal situation.

The event was so extraordinary that Time magazine put Hammond on the cover of the May 10, 1926 issue and ran a biographical sketch on him called "Unique".

He married Natalie Harris (1859–1931), of Harrisville, Mississippi (40 miles SSW south of the state capital, Jackson) on January 1, 1881, in Hancock, Maryland.

[6] The Franklin Institute awarded John Hays Hammond Jr. the Elliott Cresson Medal for life achievement in 1959.