Cosby joined the
Royal Navy as an ordinary seaman in 1747. He was given command of a schooner at the
Siege of Louisbourg in 1758 and was present at the capture of
Quebec in 1759. He was appointed
Commander-in-Chief, Mediterranean Fleet in 1785, Commander-in-Chief at Cork in 1790, and
Port Admiral at Plymouth in 1792. ==Family==