during
World War I with the unit colours in
Paris, 1919 The first flag used for
Siam was probably a plain red one, first used under
Narai (1656–1688). Naval flags later used different symbols on the red ground—a white
chakra, or the
Hindu mythological elephant
Airavata inside the chakra. Officially the first flag was created in 1855 by
Mongkut (Rama IV), showing a white elephant on red ground, as the plain coloured flag was not distinct enough for international relations. In 1916 the flag was changed to show a white elephant in royal regalia. In 1916, the current design, but with the middle colour being the same red as the outer stripe, was defined as the
civil ensign. 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. Initially (1916/17), this was a purely red and white design of five horizontal stripes. Later in 1917, the middle colour was changed to dark blue, which was similar in tone to indigo or purple, which at the time was regarded as the auspicious colour for Saturday, the day Vajiravudh was born. 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.
Historical national flags == Maritime flags ==