William Henry Blackmore was an English lawyer who gained a fortune by exploiting a large social network as an investment promoter of Spanish-Mexican Land Grants in New Mexico and Colorado between 1863 and 1878 . He used his fortune for philanthropy, primarily centred on his interest in Native Americans, but came to a tragic end as the result of a failed investment deal related to the Denver and Rio Grande Western Railroad.
On 14 May 1851 William married Mary Sidford. The couple entertained many prominent people of the time at Shepley House in Carshalton, south of London, including: Oliver Wendell Holmes, Sr., Alfred, Lord Tennyson, "Mark Twain", John Russell Bartlett, Sir John Evans, Sir Arthur Church, Ernest Griset (the artist), Sir John Lubbock, Colonel Lane Fox, Joseph W. Prestwick, and Charlotte Brontë.
General William Jackson Palmer needed financing for the Denver and Rio Grande Railroad which Blackmore placed primarily with a party of Dutch bankers. Blackmore became an investor in the United States Freehold Land and Emigration Company Limited which promoted emigration, particularly from Holland and Germany, to the 500,000 acre Costilla Estate in the San Luis Valley, Colorado Territory.
In the fall of 1868 Blackmore traveled west to inspect the completion of the transcontinental railroad, locate likely mining ventures and to investigate the Mormons. At the start of the trip Colonel Edward Bridges and Blackmore participated in a buffalo hunt oranized by General Henry B. Carrington. On the train they joined Government commissioners, Mitchell and Latham, Thomas C. Durant, General Grenville M. Dodge, Samuel B. Reed, Colonel Silas Seymour, Colonel Richard Irving Dodge and Professor Ferdinand Hayden. West of Laramie, Wyoming, Blackmore and Bridges left the train to travel to Salt Lake City, Utah in order to make confidential reports to unidentified industrial leaders and the British Cabinet. There was much publicity in the eastern states that the mormons would not trade with non-mormons, and in Britain there were concerns raised on the large numbers of British subjects who had left to join the Mormons in Utah. From October 6th to 10th 1868 John Willard Young escorted the men providing information and guiding them around the area. Others they met with include Bishop John Sharpe, David Durant, William Henry Hooper, President Brigham Young and his son Joseph Angell Young.
On a trip to the U.S. aboard the SS Russia in 1871 with Generals Sheridan, Forsyth, and Ledlie Blackmore was introduced to Abraham Lincoln's widow and son, Robert Todd Lincoln. Robert later became involved in one of William’s land deals.
Having been unsuccessful in his efforts to sell the 1300-piece Mound City Group collection to the Smithsonian Institution or the New York Historical Society, Davis prepared a catalogue featuring his cumulative collections and placed them up for sale on the open market. The catalogue included not only Ohio antiquities, but those from his excavations in Peru, Central America, and Denmark as well. Davis preferred having the collection remain in the United States, but no American institution came forward to make a serious monetary offer. In 1864 Blackmore acquired the entire collection of native American archaeological artefacts excavated from the mounds in the Mississippi valley, including the Squier-Davis collection. He purchased this collection from Davis for US$10,000.
William founded the Blackmore Museum in Salisbury which opened in a lavish ceremony on 4 September 1867.. Dr. Humphrey Purnell Blackmore(1822-1929)and William's brother in law Edward Thomas Stevens(1828-1878) were the museum's honorary curators. Since the museum collections included the Squier and Davis collections it appears to have become something of a place of pilgrimage for American archaeologists. The 1907 edition of the Encylopaedia Britannica described the museum as “one of the finest collections of prehistoric antiquities in England.” In 1899 the eminent U.S. ethnographer George Amos Dorsey (1868-1931) wrote; “The Blackmore Museum of Salisbury contains one of the best selected and arranged collections of man’s prehistoric relics that I have ever seen.” William significantly sponsored the 1872 survey expedition of the Yellowstone region lead by Ferdinand Hayden, also funding equipment for photographer William Henry Jackson and painter Thomas Moran. William and his wife travelled with the expedition. Hayden named a newly discovered mineral Blackmorite in thanks for William's support.
Blackmore commissioned photographers like Jackson to photograph Native Americans. Some accompanied the survey expeditions, some he contacted and acquired their existing prints and some made portraits of natives visiting Washington. The work of some twenty-eight photographers were to be found in Blackmore’s photographic collection. These included Antonio Zeno Shindler (d.1899), Alexander Gardner (1821-1882), Orloff R. Westman, and Dr. William Abraham Bell (1841-1920). The collections also included commercially available carte de vistes and stereoscopic views.
William took prints for display at the museum but asked that the negatives be left for students to study. The original set of photographs is referred to as the Blackmore Collection. Some photographers continued to make portraits after Blackmore left and those expanded were named for the photographer.
His brother, Dr. Humphrey Purnell Blackmore, a physician, surgeon and archaeologist was one of the founders of the Salisbury and South Wiltshire Museum which was primarily dedicated to local artifacts. In 1902 the two museums were amalgamated, taking the latter name. Following Humphrey Blackmore's death, a significant number of Blackmore Museum artifacts were distributed to other museums including the Smithsonian Institution, the Birmingham Museum, and the British Museum. In 1932 Barbara Aitken, an prominent anthropologist who had worked with the innovative educator and passionate amateur archaeologist Edgar Lee Hewett (1865-1946), secured a substantial set of Blackmore’s papers relating to his activities in New Mexico for the Historical Society of New Mexico. This material also included some 112 photographs in carte de visite, stereoscopic, Cabinet and other formats. Blackmore's museum, whose name had become incorporated with that of the Salisbury and South Wiltshire Museum after his death – and amalgamated in 1902 - finally disappeared in 1968. The remnants of his museum moved from its purpose built setting adjoining the Salisbury and South Wiltshire Museum in St. Ann Street to The King's House in the Cathedral Close in 1981 and the building was subsequently converted into residential apartments.
A world recession hit in the 1870s, investors became agitated, American partners were taking advantage of William's absence leading to a stressful situation for the promoter. In 1871 he sent his brother Henry and cousin George Blackmore and their families to look after lands in Colorado and in 1877 his sister Blanche and her husband Arthur Boyle (1840-1910), whom she had married in that year, to look after property in New Mexico. Back in England William was suffering from a fall, overwork, lack of rest and over-indulgence. Humphrey prescribed some time away in the South of England. However, after a drinking binge he suffered a sun stroke, returning home in worse condition. On 12 April 1878 William shot himself in his study.