1728- 95. He was born on 23 April 1728 in Fentonwoon, Lanteglos-by-Camelford, near Camelford, Cornwall, the son of a local landowner.
Having seen service in the Austrian War of Succession as a midshipman, Wallis was commissioned lieutenant on 19 October 1748.
He served aboard the Plymouth guardship Anson 60, Captain Charles Holmes in 1753, held a commission aboard the Gibraltar 20, Captain John Hollwall, in 1755, and thereafter moved to Vice-Admiral Hon. Edward Boscawen?s flagship Torbay 74, Captain Charles Colby. In February 1756 he removed with these officers to the Invincible 74.
On 30 June 1756 Wallis was promoted commander of the Swan 10, serving in the Western Squadron, and on 8 April 1757 he was posted captain of the Port Mahon 20, going out to North America and participating in operations at Louisbourg during the following year. In September he was appointed to the Prince of Orange 70, serving at the capture of Quebec in 1759 and then joining Commodore Lord Colville?s squadron in the St. Lawrence in the early summer of 1760 before returning to home waters later that year. In April 1761 he served under Commodore Hon. Augustus Keppel in the expedition to Belleisle and the subsequent attack on the French works on the Isle d?Aix under Captain Sir Thomas Stanhope, and he retained the Prince of Orange until the end of the war.
In the summer of 1766 Wallis was appointed to the exploration vessel Dolphin 24, which had been made famous by Captain Hon. John Byron, and he undertook a voyage to the southern hemisphere in company with the Swallow, Captain Philip Carteret, and a storeship, the Prince Frederick. Sailing from Plymouth on 22 August, they visited Madeira and the Cape Verde Islands before reaching Patagonia in the middle of December. During April 1767 the Swallow parted company when the two ships finally exited the Magellan Straits, and Wallis? next landfall was at Tahiti in June, which he named King George Island. Here some hostility was experienced with the natives before matters were resolved and provisions could be obtained, and Wallis was also able to recover his health which had suffered during the voyage. By the end of November, after visiting the Northern Mariana Islands and Uvea which he renamed Wallis Island, the Dolphin had arrived at Batavia. Here a fever ravaged the ship, leaving several men dead and not dissipating until some time after she had cleared the port. A heavy storm did considerable damage as she passed through the Indian Ocean, but eventually the Dolphin reached the Cape on 4 February, and she departed a month later to return to Plymouth on 20 May 1768, a passage of six hundred and thirty-seven days. Wallis? recommendations relating to Tahiti and the observation of the transit of Venus resulted in Captain James Cook?s first voyage of exploration being diverted to that island.
During the Falkland Islands dispute of 1770 Wallis accepted the command of the Torbay 74, retaining her throughout the following year at Plymouth and taking aboard many volunteers from his native county.
His next command was that of the Dublin 74 from October 1779 until October 1780, serving in the Channel fleet but missing the Moonlight Battle of 16 January 1780 when she became disabled and had to be escorted to Lisbon by the Shrewsbury 74, Captain Mark Robinson. After participating in the Channel Fleet campaign from June 1780 he left the Dublin in October.
Wallis resigned from active service to become an extra commissioner of the navy in October 1782, a post he held until the peace of 1783. He then resumed this position in October 1787, and he was still holding it at the time of his death in London on 21 January 1795.
He was apparently not a particularly keen explorer, and it was felt by many that he could have achieved far more during his voyage of discovery. His many paintings and drawings nevertheless were excellent. His residence in later life was at Seymour Street, London.