Asked by the Ottoman finance minister to survey the oil of Mesopotamia, a young engineer never left home. Calouste Gulbenkian read travel books, questioned railway engineers, and produced a report accurate enough to persuade the Sultan to buy the land. Born in Constantinople in 1869 to a wealthy Armenian family in the kerosene trade, he earned a first-class degree from King’s College London at 18. Then the Hamidian massacres of 1896 drove his family to Egypt, and the prodigy became a refugee.

That loss shaped his method. He stopped trying to own things outright and made himself the indispensable broker between rivals, taking a small permanent share of what they built together. He helped merge Royal Dutch and Shell in 1907, assembled the Turkish Petroleum Company in 1912, and outmaneuvered the British after the First World War by allying with France. This episode follows the fortune that resulted, the 6,400 piece art collection it bought, and the man who died in a Lisbon hotel suite in 1955 at the age of 86.

• The 1928 Red Line Agreement barred the partners from drilling alone anywhere inside the former Ottoman Empire, and Gulbenkian’s 5 percent was written into it.
• In the late 1920s and 30s he bought works by Rembrandt, Rubens, and Titian directly from the Soviet Union as Stalin’s government sold art from the Hermitage for foreign currency.
• He required that 5 percent of the workforce producing his oil for the Iraq Petroleum Company be of Armenian descent, and funded the St. Sarkis church in London and a library of over 100,000 books in Jerusalem.
• After he followed the diplomatic corps to Vichy France, Britain classified him as an enemy alien and sequestered his oil shares for the duration of the war.
• He refused a British knighthood in 1952 and left most of his wealth and all of his art to the Calouste Gulbenkian Foundation in Lisbon.