October 6 1973, the Yom Kippur War – mainly involving Egypt, Syria and Israel –triggered one of the biggest energy crises of the 20th century. Eleven days later, several Arab members of the Organization of the Petroleum Exporting Countries (OPEC) announced they would stop selling oil to countries supporting Israel and would cut production. The effect was immediate. Within a few months, global oil prices quadrupled. After decades of price stability, the world faced a severe shortage.