Collier was born in 1785/6,[2] the son of Admiral Sir George Collier and his wife Elizabeth Fryer. In 1794 he entered the Royal Navy aged 11 and served with the Channel Fleet for several years before being transferred to the Mediterranean to served aboard Admiral Horatio Nelson's flagship HMS Vanguard. In 1798, Vanguard and Collier were engaged at the Battle of the Nile, and he subsequently moved with Nelson to HMS Foudroyant, serving aboard until 1802 and the Peace of Amiens.[2]