This ( that the promise was false ) was inevitable. The fall of the Ottoman Empire was simply too great of a power vacuum . I'd also posit that since Saudi Arabia contains the two most holy places in Islam, and that there is a requirement to take a Haj in Islam, it's all but contradictory, at the very least extremely difficult.

Fromkin's "A Peace to End All Peace" ( ISBN-13 ‏ : ‎ 978-0805088090 ) has a remarkable capacity to provide context and is still written as a middlebrow/popular/non-specialist work. Remarkable book.