James Cook sailed from Plymouth aboard Endeavour on 25 August 1768, beginning a voyage that combined astronomy, natural history, naval surveying and British territorial ambitions in the Pacific.

Cook had recently been commissioned as a lieutenant and given command of the expedition. Its first major destination was Tahiti, where the Royal Society wanted observers to record the transit of Venus across the Sun in June 1769. Comparing observations from different parts of the world could help astronomers calculate the distance between the Earth and Sun.

The expedition carried a substantial scientific party. The wealthy naturalist Joseph Banks paid for his own group, which included the botanist Daniel Solander and artists including Sydney Parkinson. Charles Green travelled as the expedition’s astronomer.

Cook’s instructions did not end with the transit. The Admiralty also directed him to search the South Pacific for the supposed Great Southern Continent. His orders included provisions for claiming suitable territories for Britain.

Endeavour reached Tahiti in April 1769, and the transit was observed on 3 June. The expedition then moved into the exploratory part of the voyage. Cook sailed around New Zealand and later reached Australia’s eastern coast. Tupaia, a Raiatean navigator and priest who joined the expedition in the Pacific, provided geographical knowledge and could communicate with people encountered during parts of the voyage.

Banks, Solander and their colleagues collected and recorded large numbers of plants and animals. Cook charted extensive stretches of coastline. The voyage also brought Europeans into contact with Indigenous communities whose lands were being surveyed and, in some places, claimed for Britain.

Contemporary records can appear to disagree over the date Endeavour left Plymouth. Joseph Banks recorded the departure on 25 August. Cook placed it in his journal entry for 26 August because naval journals used a day beginning at noon. In civil time, Endeavour sailed on 25 August 1768.