The Singapore strategy was the cornerstone of British Imperial defence policy in the Far East during the 1920s and 1930s. By 1937, according to Captain Stephen Roskill, "the concept of the 'Main Fleet to Singapore' had, perhaps through constant repetition, assumed something of the inviolability of Holy Writ". With the time, many problems became apparent. One of the problems was that implementing the strategy cost a lot of money. Other difficulties were of a political or practical nature. Because of all these problems, the strategy could not be implemented. During the 1930s, the strategy was constantly criticised in Britain and abroad. Australia used the strategy to spend as little money as possible on the defence of the country. The strategy ultimately led to the despatch of Force Z to Singapore and the sinking of the "Prince of Wales" and "Repulse" by Japanese air attack on 10 December 1941. The subsequent ignominious fall of Singapore was described by Winston Churchill as "the worst disaster and largest capitulation in British history". The Japanese Occupation of Singapore began.