A brief note on stamps of Kenya, Uganda and Tanganyika overprinted "OFFICIAL": these issues were prepared by, and under the exclusive authority of, the Tanganyika postal authorities, and are listed under that country.
The largest island in the Indian Ocean is the island of Madagascar. This area was a former French colony until it achieved independence in 1958, as the Republic of Malagasy, later the People's Republic of Malagasy. The city of Diego Suarez was a major French Indian Ocean naval base in the 1800's, and was an independent French Colony from 1885 until 1896. Stamps were issued with the name "Diego Suarez" from 1890 until 1895. The majority of these are French Colonies issues overprinted for use in Diego Suarez, or Navigation and Commerce keytypes inscribed "Diego Suarez et Dependencies" or "Diego Suarez".
The French had several other colonies in the area near Madagascar. The Comoro Islands gave rise to several stamp issues, including Grande Comoro, Anjouan, Mayotte, Nossi-be, and Moheli. The stamps of these individual islands were replaced by stamps for the Madagascar colony until 1946. Stamps for the united colony of Comoro Islands were issued from 1950 until 1975. Anjouan, GRand Comoro and Moheli united in 1975 to form the State of Comoro, while Mayotte remained a French Overseas Department. Stamps inscribed "Mayotte" were re-introduced in 1997. Stamps were briefly issued for the island of Sainte Marie de Madagascar, before this territory was incorporated into the French Madagascar colony.
Another overseas department in the Indian Ocean that issued stamps as a French colony is the island of Reunion. Stamps inscribed "Reunion" were issued from 1852 until 1974, when they were replaced by regular French stamps. Manyof the issues are regular French stamps overprinted "CFA", which stands for "Colonies Francais d'Afrique", which refers to the French African Frank, a monetary unit shared by all French African colonies after 1945.
The British also had colonies in the western Indian Ocean: Mauritius and Seychelles. The island of Mauritius is famous for the "Post Office" error on the first issue. Mint copies of this stamp are valued at over $1 million! The island became independent in 1968, but remained a part of the British Commonwealth. Seychelles, a group of more than 90 islands in two main groups, forms the other former British colony. The islands were originally included in the Mauritius colony, but became a separate colony in 1903. The outer islands - Aldabra, Desroaches, and Farquahr, were included in the British Indian Ocean Territory from 1968 until 1976, when they were returned to Seychelles when that nation gained independence. As a note (since the British Indian Ocean Territory is not strictly an African entity), stamps for the British Indian Ocean Territory were issued only from 1968 until 1976, when the three populated islands were returned to Seychelles, and after 1990, when the main island in the Chagos Group, Diego Garcia, became a major British and US staging base for Indian Ocean and Middle East operations in the Gulf War.
