Flag of Thailand
|Design||Five horizontal stripes of red, white, blue, white and red, the middle stripe twice as wide as the others. |
The first flag used for Siam was probably a plain red one, first used under King Narai (1656–1688). Naval flags later used different symbols on the red ground—a white chakra (the weapon of god Vishnu which use as the symbol of the House of Chakri), or a white elephant inside the chakra.
Officially the first flag was created in 1855 by King Mongkut (Rama IV), showing a white elephant (a royal symbol) 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 1917, the current design, but with the middle colour being the same red as the outer stripe, was defined as the civil ensign. The story goes that during a flood King Vajiravudh (Rama VI) saw the flag hanging upside-down, and to prevent this from happening again created a new flag which was symmetrical. Later in 1917, the middle colour was changed to dark blue, which was similar in tone to indigo, which at the time was regarded as the auspicious colour for Saturday, the day King Vajiravudh was born. According to other sources, the blue colour 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 colours are said to stand for nation-religion-king, an unofficial motto of Thailand, red for the land and people, white for religions and blue for the monarchy, the last having been the auspicious colour of Rama VI. As the king had declared war on Germany on July 1917, some note the flag now bore the same colours as those of Britain, France, and the United States.