1917 -

The red flag with white stripes was used as the national flag in 1917 and was changed its design in the same year. King Rama VI, who originally used the red and white striped flag as the national flag, was suggested by a columnist of the Bangkok Daily Mail Newspaper that a central stripe of red should be changed to blue. The reasons for the changing were that blue was the colour of the King and the red white blue coloured flag, which was similar to the national flags of alliances, would remind the participation of Thailand in the World War I. The King agreed with this idea and declared the Flag Act B.E.2460 (1917) stating that the red white blue coloured flag, which was known as Trairanga Flag, was the national flag of Thailand.