Detailed chart of Singapore to Pulau Merambong.

Singapore was at the time undergoing significant dock and naval works in order to counter the increasingly ambitious Japanese Empire. The works - completed in 1939 at the cost some $500,000 - boasted the largest dry dock in the world, the third largest wet dock, and enough fuel tanks to support the entire Royal Navy for six months. The city was protected from naval attack by Royal Naval 15 inch guns and a Royal Air Force squadron based at Tenagh Air Base. Churchill was proud enough of its fortifications to boast of it as the "Gibraltar of the East". However, pride often comes before a fall and on the 15th February 1942, after just 15 days of fighting Singapore was under Japanese control. Some 130,000 allied troops were taken prisoner; Churchill called it the "worst disaster and largest capitulation in British history".

The British Hydrographic Office was founded in 1795 by George III, who appointed Alexander Dalrymple as the first Hydrographer to the Admiralty. The first charts were produced in 1800. Unlike the U. S. Coast Survey the Hydrographic Office was given permission to sell charts to the public and they produced a great number of sea charts covering every corner of the globe. Most of the Admiralty charts produced by the Hydrographic Office delineated coastline as well as high and low water marks and record depth of water as established by soundings. In addition these charts included information on shoals, reefs, and other navigational hazards that plagued mariners across the world. Thanks to the innovations of Sir Francis Beaufort, who developed the Beaufort Scale of wind strength, the British Hydrographic Office became one of the leading producers of sea charts. In fact, such was their accuracy that the phrase 'Safe as an Admiralty Chart' was coined.