Englishman Sir Francis Drake very probably located the island on the final lap of his circumnavigation of the world (1577–1580). 3 - Further visits by other English explorers followed, and, once St Helena’s location was more widely known, English ships of war began to lie in wait in the area to attack Portuguese carracks on their way home from India. In developing their Far East trade, the Dutch also began to frequent the island.

The Dutch Republic initially made a formal claim to St. Helena in 1633 but did not settle the isle. The English claim to the island dates to a belief that the explorer Sir Francis Drake visited the island. In 1657, the English East India Company was granted a charter to govern St Helena by Oliver Cromwell - and the following year the Company decided to fortify the island and colonise it with planters. The first governor, Captain John Dutton, arrived in 1659, and it is from this date that St Helena claims to be Britain’s second oldest (remaining) colony (after Bermuda). A fort was completed and a number of houses were built. After the restoration of the English monarchy in 1660, the East India Company received a Royal Charter giving it the sole right to fortify and colonise the island. The fort was renamed James Fort and the town Jamestown , in honour of the Duke of York and heir apparent, later King James II of England.

In subsequent geopolitical machinations, the other islands eventually passed to the newer United Kingdom as the British Empire grew into a world wide Imperial power. The most important and first settled, the island of Saint Helena, had been governed by the East India Company since 1659 and was made a British crown colony on 28 August 1833. Unoccupied Ascension Island was garrisoned by the Royal Navy on 22 October 1815, when its location in the equatorial doldrums became less important relative to its strategic importance as a centrally positioned naval coaling station. For similar reasons Tristan da Cunha was annexed as a dependency of the Cape Colony (British South Africa) on 14 August 1816 at the settlement of the Napoleonic wars.

The union between these colonies began to take shape on 12 September 1922, when Ascension Island became a dependency of Saint Helena by letters patent. Lightly populated Tristan da Cunha, even today little more than an outpost with a population of less than three hundred, followed suit on 12 January 1938. The three island groups shared this constitutional relationship until 1 September 2009, when the dependencies were raised to equal status with Saint Helena and the territory changed its name from "Saint Helena and Dependencies" to "Saint Helena, Ascension and Tristan da Cunha".

During the years of the Battle of the Atlantic of World War II and the following several years of struggle against the u-boat menace in the Atlantic, both St. Helena and Ascension Island were used to base patrolling anti-surface-commerce-raider and anti-submarine warfare (ASW) forces by the United Nations (allies) against the axis powers' naval units.

Initially long range naval patrol flying boats were used in the effort, and later in the war during the struggle to improve air coverage over the commercially important sea lanes (SLOC), air strips were built to support land based aircraft which supplied, augmented and complemented the PBY Catalina patrol planes in the vitally important ASW mission. The United States and Great Britain still jointly operate the airfield on Ascension Island, which also serves as a space-based communications and navigation nexus and hub (Ground station). One of only five Global Positioning Satellite (GPS) system ground stations is located there.