Born to a Royal Navy warrant officer of Irish extraction, also named John Conn, he was baptised at Stoke Damerel, Devon, on 5 August 1764.

[1] Conn first went to sea in 1778, aged thirteen, aboard on his father's ship Weazel, before securing a place on Arrogant as a midshipman, and in which he saw action at the battle of the Saintes in April 1782.

Making up for the delay, Dreadnought tangled with the San Juan Nepomuceno, rescuing the battered Bellerophon, killing the Spanish captain Cosmé Damián Churruca and forcing his ship to surrender.

Admiral's rank and the honours which came with it were surely not far away when tragedy struck on 4 May when during the chase of a small French ship near Bermuda, Conn became over-eager, slipped and fell overboard.

Sir John Borlase Warren, an old commander and friend, expressed regret at the death of "so deserving an officer as Captain Conn."