At an early age he went to sea as midshipman under Captain Robert Barlow, who commanded the frigate HMS Phoebe.

The high casualty count was due to the soldiers remaining on deck as a point of honor, even though they could not contribute to the battle.

On 4 February 1804 he took part in a cutting out expedition that captured the 16-gun French privateer Curieux at Fort Royal harbour, Martinique.

Their gunfire wounded Bettesworth in the thigh, causing substantial loss of blood, and broke the coxswain's arm.

After forty minutes of hard fighting the Frenchman, which had a larger crew than Curieux, maneuvered to attempt a boarding.

His information led to Rear Admiral Robert Calder's interception of the Franco-Spanish fleet at the Battle of Finisterre.

In July 1806, he became captain of the 22-gun Banterer-class post ship HMS Crocodile, on the Guernsey station, and later Halifax, Nova Scotia.

A French privateer had captured Walker, but her crew has subsequently recaptured their ship when Crocodile came on the scene and escorted her to Halifax.

That month his cousin, the poet Lord Byron, wrote: The promised voyage never took place and on 16 May 1808 Bettesworth died in the Battle of Alvøen .