Complex sentence: Pellew swam out to the wreck with a line and helped rig a lifeline which saved almost all aboard: for this feat he was, on 18 March 1796 created a baronet.
Split into simpler sentences: Pellew swam out to the wreck with a line and helped rig a lifeline which saved almost all aboard. For this feat he was, on 18 March 1796 created a baronet.