Anson's voyage around the world
In 1740, he accompanied George Anson on his voyage around the world as a midshipman aboard one of the several ships in the squadron.
On 14 May 1741, HMS Wager was shipwrecked on the coast of Chile on what is now called Wager Island, and Byron was one of the survivors. Under the tenuous command of Captain David Cheape, who was only promoted to the position mid-voyage following the death of his predecessor, the survivors bickered amongst themselves and split into factions. A large group of sailors, including Byron, eventually defied Cheape's authority and sailed east to Portuguese Brazil, targeting Rio Grande do Sul on the Atlantic coast. Days into the journey, Byron and several others returned to the captain and his remaining small party.
Cheape's party consisted of 19 men after the deserters rejoined the camp. This included the surgeon Elliot and Lieutenant Hamilton, as well as Byron and fellow midshipman Alexander Campbell. They rowed up the coast but were punished by continuous rain, headwinds, and waves that threatened the boats. One night, while the men slept on shore, one of the boats capsized while at anchor and was swept out to sea with its two boatkeepers. One of the men got ashore, but the other drowned. As it was now impossible for them all to fit in the remaining boat, four marines were left ashore with muskets to fend for themselves. The winds prevented them from getting around the headland, so they returned to pick up the marines, only to find them gone. They returned to Wager Island in early February 1742. With one death on the journey, there were now 13 in the group.
Martín Olleta, a Chono chieftain, guided the men up the coast to the Spanish settlements on Chiloé Island, where they set out again. Two men died; after burying the bodies, the six seamen rowed off in the boat, never to be seen again, while Cheape, Hamilton, Byron, Campbell, and the dying Elliot were on shore looking for food. Olleta then agreed to take the remaining four on by canoe for their only remaining possession, a musket. The party likely travelled across Presidente Ríos Lake in the inland Taitao Peninsula, a lake that Chile officially discovered in 1945. Eventually they made it to be taken prisoner by the Spanish. The Spaniards treated them well and they were eventually taken to the inland capital of Santiago where they were released on parole. The Spaniards heard that Anson had been generous in the treatment of the prisoners he had taken, and this kindness was returned.
Byron and the other three men stayed in Santiago till late 1744 and were offered passage on a French ship bound for Spain. Three accepted the passage. Campbell elected to take a mule across the Andes and joined the Spanish Admiral Pizarro in Montevideo on the Asia only to find Isaac Morris and the two seamen who had been abandoned in Freshwater Bay on the Atlantic coast. After time in prison in Spain, Campbell reached Britain in May 1746, followed by the other three two months later.
In England, the official court martial examined only the loss of the Wager, in which Baynes, in nominal charge at the time, was acquitted of blame but reprimanded for omissions of duty. Disputes over what happened after the wreck were instead played out as Bulkeley and Cummins, Campbell, Morris, the cooper Young, and later Byron published their own accounts, the last of which was the only one that in any way defended Cheap, who had since died. Twenty-nine crew members plus seven marines made it back to England.
Byron's account of his adventures and the Wager Mutiny are recounted in The Narrative of the Honourable John Byron (1768). His book sold well enough to be printed in several editions.
Byron was appointed captain of HMS Siren in December 1746.