Asserting that the desire to control the Persian Gulf's oil supply sent the United States to war against Iraq in both 1991 and 2003, this work develops a nuanced argument around that claim. It explains how the Persian Gulf came under the control of a 'system' or a cartel -- a coercive arrangement designed to ensure benefits to members and deny them to outsiders. The evolution of the oil system in the United States from its roots in Pennsylvania entrepreneurs to the Texas 'wildcatters' is traced through the dominance of the oil barons in the Standard Oil era. Further, each United States conflict in Central Asia is analysed, and the central role of oil in those conflicts is revealed. A new introduction and postscript address the motivations behind the most recent war in Iraq.