How would the French fleet have fared if it sailed from Mers-el-Kebir to fight Somerville's force?
Short answerPoorly: Somerville's ships were in better order and waiting, although the Royal Navy would not have escaped without damage.
NotesThe French formation's advantages lay in speed and maneuver. Somerville's fleet was in better order, waiting for a sortie, and equipped with powerful ships for a gun battle. The assessment favors the British force in that encounter. It also explicitly expects the British to suffer damage.