Cook's first posting was with HMS Eagle, serving as able seaman and master's mate under Captain Joseph Hamar for his first year aboard,
His first temporary command was in March 1756 when he was briefly master of Cruizer, a small cutter attached to Eagle while on patrol
In June 1757 Cook formally passed his master's examinations at Trinity House, Deptford, qualifying him to navigate and handle a ship of the King's fleet.
He then joined the frigate HMS Solebay as master under Captain Robert Craig.
During the Seven Years' War, Cook served in North America as master aboard the fourth-rate Navy vessel HMS Pembroke.[18] With others in Pembroke's crew, he took part in the major amphibious assault that captured the Fortress of Louisbourg from the French in 1758, and in the siege of Quebec City in 1759. Throughout his service he demonstrated a talent for surveying and cartography and was responsible for mapping much of the entrance to the Saint Lawrence River during the siege, thus allowing General Wolfe to make his famous stealth attack during the 1759 Battle of the Plains of Abraham.
Cook's surveying ability was also put to use in mapping the jagged coast of Newfoundland in the 1760s, aboard HMS Grenville.
He surveyed the northwest stretch in 1763 and 1764, the south coast between the Burin Peninsula and Cape Ray in 1765 and 1766, and the west coast in 1767.
At this time, Cook employed local pilots to point out the "rocks and hidden dangers" along the south and west coasts. During the 1765 season, four pilots were engaged at a daily pay of 4 shillings each: John Beck for the coast west of "Great St Lawrence", Morgan Snook for Fortune Bay, John Dawson for Connaigre and Hermitage Bay, and John Peck for the "Bay of Despair".
While in Newfoundland, Cook also conducted astronomical observations, in particular of the eclipse of the sun on 5 August 1766.
By obtaining an accurate estimate of the time of the start and finish of the eclipse, and comparing these with the timings at a known position in England it was possible to calculate the longitude of the observation site in Newfoundland. This result was communicated to the Royal Society in 1767.
His five seasons in Newfoundland produced the first large-scale and accurate maps of the island's coasts and were the first scientific, large scale, hydrographic surveys to use precise triangulation to establish land outlines.
They also gave Cook his mastery of practical surveying, achieved under often adverse conditions, and brought him to the attention of the Admiralty and Royal Society at a crucial moment both in his career and in the direction of British overseas discovery.
Explorer, navigator, cartographer,
Cook's maps were used into the 20th century, with copies being referenced by those sailing Newfoundland's waters for 200 years.
Following on from his exertions in Newfoundland, Cook wrote that he intended to go not only "farther than any man has been before me, but as far as I think it is possible for a man to go".
On 25 May 1768, the Admiralty commissioned Cook to command a scientific voyage to the Pacific Ocean.
The purpose of the voyage was to observe and record the 1769 transit of Venus across the Sun which, when combined with observations from other places, would help to determine the distance of the Earth from the Sun Cook, at age 39, was promoted to lieutenant to grant him sufficient status to take the command.
For its part, the Royal Society agreed that Cook would receive a one hundred guinea gratuity in addition to his Naval pay.
The expedition sailed aboard HMS Endeavour, departing England on 26 August 1768.
Cook and his crew rounded Cape Horn and continued westward across the Pacific, arriving at Tahiti on 13 April 1769, where the observations of the transit were made.
However, the result of the observations was not as conclusive or accurate as had been hoped. Once the observations were completed, Cook opened the sealed orders, which were additional instructions from the Admiralty for the second part of his voyage: to search the south Pacific for signs of the postulated rich southern continent of Terra Australis.
Cook then sailed to New Zealand where he mapped the complete coastline, making only some minor errors. With the aid of Tupaia, a Tahitian priest who had joined the expedition, Cook was the first European to communicate with the Māori.
However, at least eight Māori were killed in violent encounters.
Cook then voyaged west, reaching the southeastern coast of Australia near today's Point Hicks on 19 April 1770, and in doing so his expedition became the first recorded Europeans to have encountered its eastern coastline.
Cook landing at Botany Bay (Kamay)
On 23 April, he made his first recorded direct observation of Aboriginal Australians at Brush Island near Bawley Point, noting in his journal: "... and were so near the Shore as to distinguish several people upon the Sea beach they appear'd to be of a very dark or black Colour but whether this was the real colour of their skins or the Cothes they might have on I know not."
Endeavour continued northwards along the coastline, keeping the land in sight with Cook charting and naming landmarks as he went. On 29 April, Cook and crew made their first landfall on the continent at a beach now known as Silver Beach on Botany Bay (Kamay). Two Gweagal men of the Dharawal / Eora nation opposed their landing and in the confrontation one of them was shot and wounded.
Cook and his crew stayed at Botany Bay for a week, collecting water, timber, fodder and botanical specimens and exploring the surrounding area. Cook sought to establish relations with the Indigenous population without success.
At first Cook named the inlet "Sting-Ray Harbour" after the many stingrays found there. This was later changed to "Botanist Bay" and finally Botany Bay after the unique specimens retrieved by the botanists Joseph Banks and Daniel Solander.
This first landing site was later to be promoted (particularly by Joseph Banks) as a suitable candidate for situating a settlement and British colonial outpost.
After his departure from Botany Bay, he continued northwards. He stopped at Bustard Bay (now known as Seventeen Seventy) on 23 May 1770. On 24 May, Cook and Banks and others went ashore. Continuing north, on 11 June a mishap occurred when Endeavour ran aground on a shoal of the Great Barrier Reef, and then "nursed into a river mouth on 18 June 1770".
The ship was badly damaged, and his voyage was delayed almost seven weeks while repairs were carried out on the beach (near the docks of modern Cooktown, Queensland, at the mouth of the Endeavour River).
The crew's encounters with the local Aboriginal people were mostly peaceful, although following a dispute over green turtles Cook ordered shots to be fired and one local was lightly wounded.
The voyage then continued and at about midday on 22 August 1770, they reached the northernmost tip of the coast and, without leaving the ship, Cook named it York Cape (now Cape York).
Leaving the east coast, Cook turned west and nursed his battered ship through the dangerously shallow waters of Torres Strait. Searching for a vantage point, Cook saw a steep hill on a nearby island from the top of which he hoped to see "a passage into the Indian Seas". Cook named the island Possession Island, where he claimed the entire coastline that he had just explored as British territory.
Cook returned to England via Batavia (modern Jakarta, Indonesia), where many in his crew succumbed to malaria, and then the Cape of Good Hope, arriving at the island of Saint Helena on 30 April 1771.
The ship finally returned to England on 12 July 1771, anchoring in The Downs, with Cook going to Deal.
Cook's journals were published upon his return, and he became something of a hero among the scientific community. Among the general public, however, the aristocratic botanist Joseph Banks was a greater hero.
Banks even attempted to take command of Cook's second voyage but removed himself from the voyage before it began, and Johann Reinhold Forster and his son Georg Forster were taken on as scientists for the voyage. Cook's son George was born five days before he left for his second voyage.
Shortly after his return from the first voyage, Cook was promoted in August 1771 to the rank of commander.
In 1772, he was commissioned to lead another scientific expedition on behalf of the Royal Society, to search for the hypothetical Terra Australis. On his first voyage, Cook had demonstrated by circumnavigating New Zealand that it was not attached to a larger landmass to the south.
Although he charted almost the entire eastern coastline of Australia, showing it to be continental in size, the Terra Australis was believed to lie further south. Despite this evidence to the contrary, Alexander Dalrymple and others of the Royal Society still believed that a massive southern continent should exist.
Cook commanded HMS Resolution on this voyage, while Tobias Furneaux commanded its companion ship, HMS Adventure. Cook's expedition circumnavigated the globe at an extreme southern latitude, becoming one of the first to cross the Antarctic Circle on 17 January 1773.
In the Antarctic fog, Resolution and Adventure became separated. Furneaux made his way to New Zealand, where he lost some of his men during an encounter with Māori, and eventually sailed back to Britain, while Cook continued to explore the Antarctic, reaching 71°10'S on 31 January 1774.
Cook almost encountered the mainland of Antarctica but turned towards Tahiti to resupply his ship. He then resumed his southward course in a second fruitless attempt to find the supposed continent. On this leg of the voyage, he brought a young Tahitian named Omai, who proved to be somewhat less knowledgeable about the Pacific than Tupaia had been on the first voyage.
On his return voyage to New Zealand in 1774, Cook landed at the Friendly Islands, Easter Island, Norfolk Island, New Caledonia, and Vanuatu.
Before returning to England, Cook made a final sweep across the South Atlantic from Cape Horn and surveyed, mapped, and took possession for Britain of South Georgia, which had been explored by the English merchant Anthony de la Roché in 1675.
Cook also discovered and named Clerke Rocks and the South Sandwich Islands ("Sandwich Land"). He then turned north to South Africa and from there continued back to England. His reports upon his return home put to rest the popular myth of Terra Australis.
Cook's second voyage marked a successful employment of Larcum Kendall's K1 copy of John Harrison's H4 marine chronometer, which enabled Cook to calculate his longitudinal position with much greater accuracy.
Cook's log was full of praise for this time-piece which he used to make charts of the southern Pacific Ocean that were so remarkably accurate that copies of them were still in use in the mid-20th century.
Upon his return, Cook was promoted to the rank of post-captain and given an honorary retirement from the Royal Navy, with a posting as an officer of the Greenwich Hospital. He reluctantly accepted, insisting that he be allowed to quit the post if an opportunity for active duty should arise.
His fame extended beyond the Admiralty; he was made a Fellow of the Royal Society and awarded the Copley Gold Medal for completing his second voyage without losing a man to scurvy.
Nathaniel Dance-Holland painted his portrait; he dined with James Boswell; he was described in the House of Lords as "the first navigator in Europe".
But he could not be kept away from the sea. A third voyage was planned, and Cook volunteered to find the Northwest Passage. He travelled to the Pacific and hoped to travel east to the Atlantic, while a simultaneous voyage travelled the opposite route
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On his last voyage, Cook again commanded HMS Resolution, while Captain Charles Clerke commanded HMS Discovery. The voyage was ostensibly planned to return the Pacific Islander Omai to Tahiti, or so the public was led to believe. The trip's principal goal was to locate a Northwest Passage around the American continent.
After dropping Omai at Tahiti, Cook travelled north and in 1778 became the first European to begin formal contact with the Hawaiian Islands.
After his initial landfall in January 1778 at Waimea harbour, Kauai, Cook named the archipelago the "Sandwich Islands" after the fourth Earl of Sandwich—the acting First Lord of the Admiralty.