March 3, 1938

By Adam Zagorin

The King of Saudi Arabia, Abd-Al-Aziz ibn Saud, had authorized a team of American engineers to explore the trackless desert bordering the Persian Gulf, an arid landscape marked only by the occasional palm-fringed oasis. He hoped they would find water. A tribal leader with precarious finances, Ibn Saud believed the Americans might discover places where he could refresh his warriors' horses and camels. But the team, from Standard Oil of California, had something else on its mind. Oil had been discovered in other countries in the region, and the engineers thought they would find more in Saudi Arabia. Over several years, they drilled more than half a dozen holes without result. In desperation, they decided to dig deeper at well No. 7. They plumbed to a depth of 4,727 ft. and finally hit what would turn out to be the largest supply of crude oil in the world.

The King did not appear to appreciate the news fully at first. It was an entire year after the discovery when he and his retinue arrived in a caravan of 400 automobiles at the pumping station of Ras Tanura to witness the first tanker hauling away its cargo of Saudi crude. Henceforth the King would no longer rely for income on the pilgrims arriving in Mecca, Islam's holiest city. And his kingdom's petroleum wealth would emerge as a crucial factor in Middle East politics and the bargaining over global energy supplies. --By Adam Zagorin