As the king declared war on Germany that July, some note the flag now bore the same colours as those of the UK, France, Russia and the United States.

[5] The colours of the flag were standardised in an announcement of the Office of the Prime Minister dated 30 September 2017, on the occasion of the 100th anniversary of its adoption.

According to a popular legend, king Vajiravudh (Rama VI) was appalled when he saw the elephant flag flown upside down by one of his subjects by accident, which caused him to order the creation of a vertically symmetrical design.

According to other sources, the blue was also chosen to show solidarity with the Allies of World War I, which also had the colours blue-red-white in their flags.

The kingdom's naval jack is the national flag defaced with the emblem of the Royal Thai Navy in the middle.