Kingdom of Tonga
1900–1970
Flag Coat of arms
Location of the Kingdom of Tonga with present-day borders shown.
Status	Protected state of the United Kingdom
Capital	Nuku'alofa
Common languages	English Tongan
Religion	Free Wesleyan Church
Government	Unitary parliamentary semi-constitutional monarchy
Monarch
• 1900–1918	George Tupou II
• 1918–1965	Sālote Tupou III
• 1965–1970	Tāufaʻāhau Tupou IV
Prime Minister
• 1900–1905	Siosateki Veikune (first)
• 1965–1970	Fatafehi Tu'ipelehake (last)
Consul
• 1901–1909	Hamilton Hunter (first)
• 1965–1970	Archibald Cameron Reid (last)
Legislature	Legislative Assembly
History
• Treaty of Friendship	18 May 1900
• End of protection status	4 June 1970
Currency	Tongan pound (1921–1967) Tongan paʻanga (1967–1970)
ISO 3166 code	TO
Preceded by Succeeded by Tonga Tonga

The Kingdom of Tonga was a protected state of the United Kingdom from 1900 to 1970, when its protectorate status was removed.

Tonga became a British protected state under a Treaty of Friendship on 18 May 1900, when European settlers and rival Tongan chiefs tried to oust King George Tupou II, and to secure the independence of Tonga amid further German territorial gains in the Pacific.^[1][2][3] The Treaty of Friendship and protected state status ended in 1970 under arrangements established prior to her death by the third monarch, Queen Sālote.

While never directly ruled by the British, Tonga's foreign affairs were conducted through the British consul, giving the United Kingdom veto power over foreign policies and finances of the Kingdom of Tonga.^[1] An unspoken agreement of the treaty that was common in British protected states was a new monopoly on Tonga's thriving vanilla industry, and their small deposits of minerals.

Tonga was affected by the 1918 flu pandemic, with 1,800 Tongans killed, around eight per cent of the residents.^[4]

For most of the 20th century Tonga was quiet, inward-looking, and somewhat isolated from developments elsewhere in the world. Tonga's complex social structure is essentially broken into three tiers: the King, the nobles, and the commoners. Between the nobles and commoners are Matapule, sometimes called "talking chiefs," who are associated with the King or a noble and who may or may not hold estates. Obligations and responsibilities are reciprocal, and although the nobility are able to extract favours from people living on their estates, they likewise must extend favours to their people. Status and rank play a powerful role in personal relationships, even within families.

Tonga gained independence within the Commonwealth of Nations on 4 June 1970.^[5]

• 
  Tomb of King George Tupou I, 1900
• 
  Tomb of King George Tupou I, 1900
• 
  King George Tupou II going to the opening of the Tongan Parliament in 1900
• 
  Richard Seddon and his wife at the opening of the Tongan parliament, 1900
• 
  The royal throne of Tonga, 1900.
• 
  World War I memorial in Nukuʻalofa
• 
  Members of the Tonga Defence Force of the 2nd NZEF on parade in Tonga celebrating the capitulation of Italy in 1945
• 
  Bishop John Rodgers, Pīsila (wife of Lord Fusitu'a(Tevita Tu'iniua),full name Pisila Fotofili Fusitu’a) and Suli Seuli (matāpule of Fusitu'a) watching dancing. Inauguration of the Catholic church in Kolofo'ou. 1967