Byron served as a midshipman on HMS Wager (which was wrecked on the coast of southern Chile) during George Anson's voyage around the world. He later wrote about the ordeal suffered by the survivors in The Narrative of the Honourable John Byron (Commodore in a Late Expedition round the World). Containing an Account of the Great Distresses Suffered by Himself and His Companions on the Coast of Patagonia, from the Year 1740 till their arrival in England, 1746 (1768). In 1760, then Captain Byron led a small naval squadron (Fame, 74 guns; Dorsetshire; 70 guns, Achilles, 60 guns; and Scarborough, 22 guns) in an expedition to assist the garrison to demolish the fortifications at Louisbourg, on Cape Breton Island, in the French colonial territory of Acadia (now Nova Scotia).
Byron set out in command of his own Pacific Ocean voyage of exploration in command of the frigate HMS Dolphin in 1764. Although the expedition failed to find the Great South Land, it did discover a number of islands and circumnavigated the globe, returning to England in 1766.
Promoted rear admiral in 1775 and vice-admiral in 1778, Byron was commander-in-chief of the Royal Navy's West Indies Squadron in 1778 and 1779. In this capacity he attempted to intercept a French fleet under Comte d'Estaing. (When he finally caught the 25-vessel French fleet off Grenada on 7 July 1779, he made a bold attack but the engagement was indecisive.) This was the last naval post Byron held before his death in 1786.
Byron is remembered by the nickname "Foul-weather Jack" because of his apparent bad luck when it came to meteorological conditions.
- CHILE 2006, Scientific Exploration Society, 2006. Retrieved on 2008-02-20. “However, once ashore a dispute arose regarding the Captain's powers of command over the soldiers who had been aboard and the sailors who, once their ship was wrecked, were no longer paid by the Navy.”
- John Byron. Dictionary of Canadian Biography Online. Retrieved on 2008-08-14.
- Fall of Louisbourg, Upper Canada History. Retrieved on 2008-08-14.
- Foul-weather Jack, Bartleby.com. Retrieved on 2008-08-14.