The flag of Tonga

Tonga

Tonga, officially the Kingdom of Tonga , is a state and an archipelago in the South Pacific Ocean, comprising 176 islands scattered over of ocean in the South Pacific...

was adopted on November 4, 1875.

The flag looks similar to the flag

Flag

A flag is a piece of fabric with a distinctive design that is usually rectangular and used as a symbol, as a signaling device, or decoration. The term flag is also used to refer to the graphic design employed by a flag, or to its depiction in another medium.The first flags were used to assist...

 of the Red Cross. The flag was originally identical to that flag, but to avoid confusion, it was changed so that the red cross appeared as a canton

Flag terminology

Flag terminology is a jargon used in vexillology, the study of flags, to describe precisely the parts, patterns, and other attributes of flags and their display.-Description of standard flag parts and terms:...

 of a red ensign

Ensign

An ensign is a national flag when used at sea, in vexillology, or a distinguishing token, emblem, or badge, such as a symbol of office in heraldry...

, making it similar to the 17th century red ensign. The flag has been in use since 1864 but was officially adopted in 1875. Clause 47 of the Constitution of Tonga

Constitution of Tonga

The Tongan Constitution was enacted by King George Tupou I on 4 November 1875. It stipulates the makeup of the Tongan Government and the balance between its executive, legislature, and judiciary. The anniversary of its passage is celebrated annually as Tonga's Constitution Day.Tonga is a...

 states: "The Flag of Tonga shall never be altered but shall always be the flag of the Kingdom."