Prettyjohns was born at Dean Prior, near to Buckfastleigh, Devon, to William Pethyjohns (1800–1889) and his wife Margaret (née Pow, 1805–1866).

[1] The 2 November 1854 was an active day, 312 rank and file marched off from the heights of Balaklava, for the Light Division, under the command of Captain Hopkins, RMLI, the detachment was divided into four companies, taking turn in the trenches.

The bugle sounded the ‘Fall-in’ at the double, and officers were flying about giving orders, saying vast columns of the enemy were moving up to our rear.

The Caves were to be cleared, and the Marines ordered to do it; as soon as we showed ourselves in the open, a broadside from the frigate thinned our ranks; Captain March fell wounded.

A division under Sergeant Richards and Corporal Prettyjohns, was then thrown out to clear the caves, what became of the Commanding Officer and the others I never knew, so many statements have been made.

We, under Richards and Prettyjohns, soon cleared the caves, but found our ammunition nearly all expended, and a new batch of the foe were creeping up the hillside in single file, at the back.

As soon as the first man stood on the level, Prettyjohns gripped him and gave him a Westcountry buttock, threw him over upon the men following, and a shower of stones from the others knocked the leaders over.

On being mustered, if my memory is not at fault, twenty-one had been killed and disabled, and we felt proud of our own Commanding Officer, who stood fine, like a hero, helping Captain March.