Operation Jericho was to mainly free 10 members of the French resistance that were set for execution the day after. With that they were wanting to rescue another 280 members of the Free French, political prisoners and general people apathetic towards the Germans. Of the total 290 set to be rescued 128 fully escaped and re-established the spy network (the main aim of the Operation). 9 of the main 10 escaped.
Most of the dead were shot by the Germans, or recaptured on their way out. The French in the prison always said though, 'we'd rather die under a RAF bomb than by a German bullet'.
The operation was a complete success, with severe losses to the German guard, and serious moral booster for the French and British, while diminishing the Germans moral in and around the Amiens prison.