In the Commonwealth of Nations, a High Commissioner is the senior diplomat (ranking as an ambassador) in charge of the diplomatic mission of one Commonwealth government to another.
British Colonial usage
Formerly, in the British Empire, the British Government appointed high commissioners to manage protectorates or groups of territories not fully under the sovereignty of the British Crown.
Historically, in the British Empire (most of which would become the Commonwealth) High Commissioners were envoys of the Imperial Government appointed to manage protectorates or groups of territories not fully under the sovereignty of the British Crown, while Crown colonies (which were British sovereign territory) would normally be administered by a Governor and the most significant possessions, large confederations and the independent Commonwealth Dominions would be headed by a Governor-General.
Cases include:
the island of Cyprus, since 12 July 1878 under British administration (previously under Ottoman military rule), Istanbul retained nominal suzerainty until the 5 November 1914 full British annexation; there were 9 incumbents (all but one already knighted) from 22 July 1878 until on 10 March 1925 Cyprus became a crown colony, and the last incumbent stayed on as its first Governor
A High Commission could also be charged with the last phase of a decolonisation, as in the crown colony of the Seychelles (12 November 1970 granted autonomy), where the last Governor, Colin Hamilton Allen (b. 1921 - d. 1993), stayed on as only colonial High Commissioner from 1 October 1975, when self-rule under the Crown was granted, till 28 June 1976 when the archipelago became an independent republic within the Commonwealth
British Protectorates
As diplomatic Residents (as diplomatic ranks were codified, this became a lower class than Ambassadors and High Commissioners) were also appointed to native rulers, that position could on occasion similarly be filled be a colonial Governor. Thus High Commissioners could be charged with managing diplomatic relations with native rulers and their states (analogous to the Resident Minister), and might have under them several Resident Commissioners or similar agents attached to each state. In present Nigeria:
Northern Nigeria, three incumbents 1900-1907, the last of which stayed on as first Governor
Southern Nigeria, three incumbent 1900-1906 (four terms), the last of which stayed on as first Governor.
In certain regions of particular importance, a Commissioner-General would be appointed, to have control over several High Commissioners and Governors, e.g. the Commissioner-General for South-East Asia had responsibility for Malaya, Singapore and British Borneo.
Governors doubling as High Commissioners
The role of High Commissioner for Southern Africa was coupled with that of British Governor of the Cape Colony in the nineteenth century giving the colonial administrator in question responsibility both for administering British possessions and relating to neighbouring Boer settlements. The best known of these High Commissioners, Alfred Milner who was named to both positions in the 1890s, is considered responsible by some for igniting the Second Boer War.
Currently, there is still one High Commissioner who also serves in an additional capacity as a Governor: the British High Commissioner to New Zealand ex officio serves as British colonial Governor of the Pitcairn Islands.
Other (mainly former, colonial) empires & protectorates
In the (post-)colonial sense, some other powers had High Commissioners, or rather the exact equivalent in their language
French
Originally the French word Haut Commissaire, or in full Haut Commissaire de la république 'High Commissioner of the Republic', was rarely used for governatorial functions, rather (Lieutenant-)gouverneur(-général) and various lower titles. Exceptions were:
since 22 March1907, the colonial Gouverneur of New Caledonia was also appointed as High Commissioner in the Pacific Ocean, to coordinate with the governors of the French Settlements in Oceania and the Governors-general of French Indochina; the French resident commissioner of the Anglo-French condominium Nouvelles Hébrides and the Residents to the island protectorates of Wallis and Futuna were subordinated to him
once Charles de Gaulle named someone else as High Commissioner for the French Territory of the Pacific and the Far East, January 1941 - 1945: Georges Thierry d'Argenlieu (b. 1889 - d. 1964), while in December 1941 the Vichy (pro-German) government named Jean Decoux (b. 1884 - d. 1963) to the post (who in fact was only responsible for Wallis and Futuna, which was the only Pacific territory not to have rallied to the Free French at that time).
In Atlantic waters, from 14 September1939 till September 1943, four French Possessions in the Americas (French Guiana, Guadeloupe and Martinique, all in the Caribbean, as well as Saint-Pierre and Miquelon, off the Canadian coast) were temporarily grouped together (from June 1940 under Vichy France, so remaining on the Allied side). The two consecutive 'High Commissioners in the Antilles' (quite a misleading title: French Guyana is in continental South America, St-Pierre&Miquelon off the Canadian coast, so in North America) held both administrative authority over the local Governors and equivalent officers (rather like a gouverneur général did elsewhere on a permanent basis) and military command in the 'Theater Atlantic West':
In the later period of decolonisation, the office of High Commissioner in a colony to become an allied nation was intended to become remarkably analogous to the Commonwealth's 'close relationship diplomats' in President General De Gaulle's project for a French Union to match the Commonwealth, but it soon started to fall apart, so they actually just presided over most of the peaceful decolonisation.
Algérie (Algeria), once similar to Tunis, but transformed into a French popular colony (most of the time under its own governor-general; then a messy period as native and immigrated European interests were irreconcilable), got its only High commissioner on 19 March1962: Christian Fouchet (b. 1911 - d. 1974), until its 3 July1962 independence from France (Algerian State; 25 September1962 People's Democratic Algerian Republic ruled by the FLN, the former armed revolt)
in present Benin, since 13 October1946Dahomey overseas territory, on 4 December1958 granted autonomy as Republic of Dahomey, the last (acting) governor, René Tirant (b. 1907), stayed on as only High commissioner till the 1 August1960 independence
Gabon had two High Commissioners since on 28 November1958 autonomy was granted (as Gabonese Republic) to the former overseas territory (since 1946)
November 1958 - July 1959 Louis Marius Pascal Sanmarco (b. 1912), also the last of the Governors since 1941 (after various otherwise styled chief executives before; it had since 15 January1910 been part of French Equatorial Africa, AEF)
Mauritania had two High commissioners, after having been a protectorate since 12 May1903 (under a single military Commandant), from 18 October1904 the French civil territory of Mauritania under a Commissioner (part of French West Africa (AOF); under its Governor-general in Dakar, Senegal), and since 12 January1920 a French colony under a Lieutenant governor (many incumbents, again under Dakar), on 28 November1958 obtaining autonomy (as Islamic Republic of Mauritania):
5 October1958 - February 1959 Henri Joseph Marie Bernard (b. 1920)
February 1959 - 28 November1960 Amédée Joseph Émile Jean Pierre Anthonioz (b. 1913 - d. 1996); since independence from France it had its own President (or a junta chief);
In Niger, since 13 October1946 an overseas territory of France (part of French West Africa, see Senegal) under a lieutenant-governor, on 19 December1958 granted autonomy as Republic of Niger, there was a single High commissioner 25 August1958 - 10 November1960: Jean Colombani (b. 1903), i.e. still several months after the formal 3 August1960 independence whilst there was no President
In Senegal, since 27 October1946 an overseas territory of France, which on 25 November1958 had obtained autonomy (as Republic of Senegal), the last Governor stayed on as first (and only?) Haut commissaire25 November1958 - 20 June1960: Pierre Auguste Michel Marie Lami (b. 1909); meanwhile on 4 April1959 the Sudanese Republic (now Mali) and Senegal formed the Mali Federation and his term ended at the 20 June1960 independence of that Mali Federation from France (on 20 August1960 the Republic of Senegal withdrew from the thus dissolved Mali Federation).
in French Sudan, an overseas territory of France since 27 October1946 (earlier a colony; stayed within French West Africa), which on 24 November1958 obtained autonomy (as Sudanese Republic), there were two High commissioners:
24 November1958 - 20 June1960 Jean Charles Sicurani (b. 1915 - d. 1977); during his term on 4 April1959 this Sudanese Republic and Senegal (cfr. above) united to form the Mali Federation; his office ceased at the 20 June1960 independence of the Mali Federation from France
11 December1958 - February 1959 Max Berthet, who stayed on, having been the last (acting) Governor
February 1959 - 5 August1960 Paul Jean Marie Masson (b. 1920), till the Independence from France as the Republic of Upper Volta.
While the colonies above were generally artificially carved creations, Haut commissaires also were appointed by Paris to prepare the (de facto) independence of pre-existing monarchies that had formally been French protectorates, such as:
Tunisia, known as the Régence (since 3 June1955 autonomous), where France had a Resident-general (posted with the Basha bey of Tunis, who once the French protectorate was terminated on 20 March1956 restyled his realm al-Mamlaka at-Tunisiyya 'Tunisian Kingdom'), in stead got a High commissioner from 13 September1955 to 20 March1956: Roger Seydoux Fornier de Clausonne (b. 1908 - d. 1985); in continued shortly as independent monarchy, but on 25 July1957 became the Tunisian Republic.
Yet a colony could achieve independence without a High Commissioner, e.g. Guinée (French Guinea).
In one case a French Haut Commissaire was the exact match and colleague of a British High Commissioner: they represented both powers in the south sea condominium (i.e. territory under joint sovereignty) of the New Hebrides, which became the present republic of Vanuatu.
A very special category was the Haut Commissaire as 'liquidator' of a gouvernement-général (the colonial echelon grouping several neighbouring colonies under a Governor-general), notably:
4 April1957 - 29 January1958 Paul Louis Gabriel Chauvet (b. 1904), also the last of the long list of Governors-general since 28 June1908 (before it had five Commissioners-general since 27 April1886)
in Afrique Occidentale Française (AOF), i.e. French West Africa, the last of a long list of Governors-general since 1895 stayed on as first of only two High Commissioners:
4 April1957 - July 1958 Gaston Custin (b. 1903 - d. 1993)
Another use for the title was found in the rare remaining insulara (formerly no longer colonial) overseas possessions, in these cases still functioning:
In French Polynesia it is the title of the representative of the French republic in the overseas territory (restyled 'overseas collectivity' in 2003, 'overseas country' on 27 February2004) since 13 July1977 (until 14 September1984 he also presided the local council of ministers, the that got its own president, as the legislature already had)
In New Caledonia (Nouvelle Calédonie in French, colonised in 1853; its Governors had been High Commissioners in the Pacific Ocean from 22 March1907, see above) the title (commonly corrupted to Haussaire) was chosen for the chief executive on 19 December1981, when it was an overseas territory (since 1946), even before autonomy was granted on 18 November1984, and maintained after its status was changed on 20 July1998 to the unique French collectivité sui generis; he represents the Paris government, while there are a native legislature and government.
Greek
On 30 July1922, the Hellenic kingdom (Greece) declared Smyrna (the Anatolian Izmir district, occupied by Greece since 12 May1919) a protectorate. Until on 9 September1922 Greece restores Smyrna to Turkey after defeat of Greek forces, it had a Greek High Commissioner (21 May1919 - 8 September1922): Aristeidis Stergiadis (b. 1861 - d. 1950)
Italian
while only various military commanders and since 1916 a Secretary for Civil Affairs in Albania (Ugo Capialbi) had acted for Rome since Italy invaded on 27 December1914 (occupying Valorë and parts of Southern Albania; on 3 June1917 Albanian independence under an Italian protectorate was declared by Italy, opposed by most Albanians; adding in November 1918 the former Austro-Hungarian occupied areas to the Italian zone) only since in 1919 an Albanian provisional government recognized by Italy as the legal government of the protected zone, consecutive High Commissioners for the Crown were appointed until Italy effectively withdraw its troops on 3 September1920 (as agreed on 22 August1920 when formally recognizing the total independence of Albania):
two incumbents appointed by the kingdom in Fiume (a former Austrian province; now Rijeka, in Croatia), after an extraordinary commissionary, in the 31 December1920 declared, short-lived "Independent State of Fiume", until the accession of its first President
13 June1921 - 1921 Antonio Foschini (b. 1872 - d. 19..)
1921 - 5 October1921 Luigi Amantea (b. 1869 - d. 19..)
in Slovenia, which after 6 - 17 April1941 Italian-German occupation, was on 17 April1941 partitioned between Italy, Hungary and Germany, the Italian portion was named province of Lubiana, from 3 May1941 under a Civil Commissioner, from 3 May1941 restyled the first of two High Commissioners:
18 April1941 - 1942 Francesco Saverio Grazioli (b. 1869 - d. 1951)
1942 - 1943 Giuseppe Lombrassa (b. 1906 - d. 1966)
Portuguese
The title Alto Comissário da República (High Commissioner of the Republic) or, simply Alto Comissário, was given to some portuguese colonial governors to who were given, excepcional, enlarged executive and legislative powers, superiors to those of common Governors. In the Monarchy, before 1910, they were known as Comissários Régios (Royal Commissioners). Had been nominated Altos Comissários or Comissários Régios for:
António Elísio Capelo Pires Veloso - 18 December1974 (three days before the formal granting of autonomy), actually the last of many governors (since 1753, before both islands were separate), staying on until it became an independent republic on 12 July1975
15 December1963 - 1964 Francisco Núñez Rodríguez (b. 1902 - d. 1972), also the last of many Governors since 7 June1494
1964 - 1966 Pedro Latorre Alcubierre
1966 - 12 October1968 Víctor Suances Díaz del Río; his term ended when it became an independent republic
The title Alto Comisario was also used for the representative of Spain in its protectorate zone within the Sherifan sultanate of Morocco (most of the country was under French protectorate), known as el Jalifato after the khalifa (Jalifa in Spanish), the Sultan's fully mandated, princely Viceroy in this protectorate, to which the High Commissioner was formally accredited, but whose senior he was in reality. In 1934 - 1956 the Governors of the Western Sahara (which from 27 November1912 were also Governors-general of Spanish West Africa) were subordinated to him. The office itself was however filled by the governors of Spanish West Africa from 1939 to 1956.
United States
While being a U.S. protectorate from 1905 to 1941, the Dominican Republic had first various native regimes, then US military Governors 29 November 1916 - 24 July 1922, and just before it again had the first of its own Presidents on 21 October 1922, a single U.S. High Commissioner, Sumner Welles, who served from 1922 - 1924.
Haiti, the other (western) half of the island of Hispaniola, had a similar experience. It was a U.S. protectorate from 1915 to 1936, after five U.S. Military Commanders, there was one High Commissioner, John H. Russell, Jr., who served from 11 February1922 to 16 November1930.
7 September1942 - 4 July1946 Paul V. McNutt (2nd commission) (to August 1945 in U.S. exile during Japanese military occupation). McNutt's termed ended with the official independence of the new republic.
Okinawa and Ryukyu Islands (Japanese archipelago), and later just Okinawa had six U.S. High Commissioners:
28 January1968 - 15 May1972 James Benjamin Lampert. On 15 May1972 Okinawa reverted to Japanese sovereignty as a prefecture; therefore, the office of U.S. High Commissioner on Okinawa ceased to exist.
High Commissioners as Extraordinary Government Agents
In many cases, a political vacuum created by war, occupation or other events discontinuing a country's constitutional government has been filled by those able to do so, one nation or often an alliance, installing a transitional (often minimal) governance administered by, or under supervision of, one or more High Commissioners representing it/them. For example:
22 November1918 - 1919 Alsace-Lorraine, till then part of the defeated German Empire as Elsaß-Lothringen but just occupied by and restored to France, was under haut commissaire Maringer (it would be only fully reintegrated in 1925, after three Commissioners General)
In France, a high commissioner, in French haut-commissaire, is a civil servant appointed by the President of France to some high level position within France:
After the naval blockade of Crete in 1898 by France, Italy, Russia and the United Kingdom, Crete became autonomous within the Ottoman Empire. These protecting powers appointed the following as High Commissioner (or "Armostis") until 1908 when the Cretan Assembly unilaterally declared union with Greece (with Crete subsequently formally becoming part of Greece in 1913):
Even shortly before on 8 December1918 the Allied occupation of the Bosporus, the Dardanelles, the eastern coast of the Sea of Marmara, the islands of Imros, Lemnos, Samothrace and Tenedos and 15 km deep into eastern and the eastern shores; entire area demilitarized (Zone of the Straits; complemented 16 March - 10 August1920 as the allies occupy the Ottoman capital Istanbul) was a military fact, in November 1918 a double post was created: until the termination of allied occupation on 22 October1923, there were at all times one British Senior Allied High Commissioner and one (junior) Allied High Commissioner (incumbents from France, thrice, Italy and the US, each twice).
Often the main/locally concerned members of an alliance would not set up a joint occupation authority (as in Italy after the Nazi defeat) but simply each appoint one for each of the zones into which they physically divided amongst themselves an occupied state or territory, e.g. after World War II:
in Austria, until 27 July1955 when Allied occupation ends, restoring Austrian sovereignty, it was administered as a British Zone (6 consecutive High Commissioners, July 1945), a US Zone (4 incumbents from 5 July1945), a Soviet Zone (4 from July 1945; only this had first been under a Military Governor from 8 April1945) and a French Zone (2, from 8 July1945);
in Germany there were also four major occupation zones: the British Zone (after three consecutive Military governors from 22 May1945, the last stayed on as first of three consecutive High Commissioners 21 September1949 - 5 May1955), the US Zone (after five Military governors from 8 May1945, four High Commissioners 2 September1949 - 5 May1955), the Soviet Zone (after a military commander April 1945 - 9 June1945 who stayed as first of three Military governors 9 June1945 - 10 October1949, the last of whom stayed on as only Chairman of the Soviet Control Commission 10 October1949 - 28 May1953, two High commissioners 28 May1953 - 20 September1955) and the French Zone (after a Military commander from May 1945 and a Military governor from July 1945, a single High commissioner 21 September1949 - 5 May1955); the Nazi capital, Berlin, enclaved in the Soviet zone, is separately quartered under four military City Commanders; only the small Dutch zone by the border is destined for annexation in 1949, so it is divided up in two districts, each under a landdrost (Tudderenen, attached to the province of (Dutch) Limburg and Elten, attached to Gelderland province), but returned to Germany after compensation payments and minor border corrections on 11 August1963
Emancipatory administrators under International law
As the 'world community' became a widely accepted ideal in diplomacy and was embodied first in the League of Nations and later the UNO, these often came to play a key role in extraordinary situations that would earlier probably have been dealt with by states as above, sometimes reflected in the appointment of High Commissioners under their auspices, sometimes just from the same leading powers, sometimes rather from 'neutral' member states.
The title of High Commissioner was specifically used for the administrators during the 'emancipation from colonial rule' of League of Nations mandates and United Nations Trust Territories, i.e. non-sovereign states under a 'transitional' regime established under the authority of the League of Nations or the UN, respectively, to prepare them for full independence.
These 'guardianships' most often were simply awarded to the former colonial power or if that was a loser in the preceding World War, to the 'liberating' Allied victor(s).
League of Nations - Mandate territories
Iraq, conquered on the Ottoman Walis by British forces, had four incumbents, after a single civilian Administrator (10 January1919 - 1 October1920 Sir Arnold Talbot Wilson), continuing ten years after the accession to the throne and most of the rule of the country's first Malik (King, reigned 23 August1921 - 8 September1933) Faysal I (b. 1885 - d. 1933) :
1 July1920 – 1925 Sir Herbert Louis Samuel (1879–1963), until the 1922 establishment of the mandate actually the first civilian who took over, already as High Commissioner, from the three consecutive military administrators since the 1917 conquest by British forces
After the former Italian colony of Eritrea had been under victor Britain's administration since 5 May1941, a specific United Nations administration, under Britain, was installed on 19 February1951, under a UN High Commissioner, Edoardo Anze Matienzo (Bolivian, b. 1902), whose office ceased on 15 September1952 when it was Federated with Ethiopia under the sovereignty of the Ethiopian emperor.
Representing the world universally
At the United Nations and affiliated global organisations, a High Commissioner serves as the permanent chief executive of a commission composed of representatives of various member nations.
the UN High Commissioner for Human Rights, who has the rank of Under-secretary-general, serves the United Nations Human Rights Commission. In fact in 2005, the US Ambassador at the UN complained that the incumbent, as a 'civil servant', was not authorized to act upon information (in this case world wide press reports on abnormal detention forms in the 'war against terrorism' suspected to breech the rights of the suspects) not obtained by the organisation's official channels.