 The aims of this first expedition were to observe the 1769 transit of Venus across the Sun (3–4 of June that year), and to seek evidence of the postulated "Terra Australis Incognita" or "undiscovered southern land".The voyage was commissioned by King George III and commanded by Lieutenant James Cook, a junior naval officer with good skills in cartography and mathematics.Departing from Plymouth Dockyard in August 1768, the expedition crossed the Atlantic, rounded Cape Horn and reached Tahiti in time to observe the transit of Venus.