Charles de Gaulle (French president at that time) withdrew from the pool and demanded Gold for the US dollars they held instead of US-treasuries. The drain on US gold became acute.

This rings a bell! Holding the gold price artificially down - in fact - created even more demand. The more London Gold-pool reaffirmed its determination to defend the $ 35.20 per oz gold price (ironically), the more gold was bought and the more Gold the pool had to deliver. As the London Gold pool continued to fight the free market process by defending $ 35.20 (like today they defend $ 1,000), the stronger demand became. As daily turnover mushroomed to 30 times the normal sales, the British Queen declared a "bank holiday" (upon request of the USA). The London gold market remained closed for 2 weeks while France and Switzerland continued to trade Gold at a price exceeding $ 45 per oz.

The resulting two-tier market for Gold was completely abandoned in 1970 when Nixon closed the Gold window. This was the day, the US dollar (and at the same time many other currencies which held US Dollars as Reserve) officially became Fiat Paper Money.

http://www.goldonomic.com/gold_pool.htm

http://books.google.ca/books?id=zUYo_gpyzGUC&pg=PA1996-IA25&lpg=PA1996-IA25&dq=de+Gaulle+requested++exchange+dollars+on+gold&source=bl&ots=AIwrRcSYwj&sig=3AdN3vyCsdRCYfxGnjIJg4O8J5g&hl=en&sa=X&ei=AjfwUsuzDMeSyQHs8IDgBg&ved=0CD4Q6AEwAw#v=onepage&q=de%20Gaulle%20requested%20%20exchange%20dollars%20on%20gold&f=false