During the Greater East Asia War, Thailand had entered the pact with Japanese at the end of year 1941 resulting in Thailand becoming an ally of Japan. As a result, Thailand could not order banknotes from Thomas De La Rue & Company Limited, England which caused a scarcity of banknote in the country. The Thai government thus requested the Japanese government to print banknote. Later, when the War escalated, the transport of banknotes from Japan to Thailand could not be carried out easily due to severe Allied attacks. This caused a shortage of banknotes, thus and the Thai government decided to print banknotes by using domestic materials and assigned the Royal Thai Survey Department, the Naval Hydrographic Department, and other printing houses to print banknotes.
Their features were like the 4th series printed by Thomas De La Rue. However they were printed by the Royal Thai Survey Department instead. As a result, these notes had contained a phrase "the Royal Thai Survey Department" at the lower center of the front and back. This notes series had been printed by using a paper from Thai paper factory, Kanchanaburi. There were 4 denominations: 1, 10, 20 and 100 Baht. Each denomination had two types, however some denominations had only one type. They had been started using in 1942.
Japanese troop marching through Thailand to Malay
The Alliance treaty signing between Thailand and Japan
Thai paper mill in Kanchanaburi