This book explores the changing balance of power in the Persian Gulf in the four years after the British announced their decision to withdraw forces from the Gulf in 1968, ending 150 years of military supremacy in the region. The British system was accepted for more than a century not merely because the British were the dominant military power in the region. The balance of power mattered, but so did the framework within which the British exercised their power. The search for a new framework for regional politics, which began when the British announced their withdrawal, was not simply a matter of which ruler would amass enough military power to fill the void left by the British: it was also a matter of the Gulf rulers – chiefly Iran, Iraq and Saudi Arabia – coming to a shared understanding of when and how the exercise of power would be viewed as legitimate. This book explores what shaped the rulers’ ideas and actions in the region as the British system came to an end, providing a much-needed political history of the region in the lead-up to the creation of the UAE in 1971.