Oil arrived as a curiosity — a medicine, a lamp fuel, a substitute for whale oil — and within fifty years had become the most strategic commodity on Earth. The first commercial well was drilled in Pennsylvania in 1859. By 1911 a single American family controlled most of the world's refined oil. By 1914 the British Royal Navy had switched from coal to oil at Churchill's insistence, and the country with the best oil reserves was no longer Britain. The 20th century is, in plain economic terms, the century the energy capital moved from Tyneside to Texas — and from Texas, eventually, to Riyadh.