the youngest of three brothers born to an aristocratic, landowning family, descended from john codrington, reputed to be standard-bearer to henry v at agincourt, and related to the codrington baronets, codrington was educated by an uncle named mr bethell. he was sent for a short time to harrow, and entered the royal navy in july 1783. he served off the eastern seaboard of the united states, in the mediterranean and in home waters, until he was promoted to lieutenant on 28 may 1793, when lord howe selected him to be signal lieutenant on the flagship of the channel fleet at the beginning of the french revolutionary wars. in that capacity he served on the 100-gun during the operations which culminated in the battle of the glorious first of june.