Propulsion while surfaced was provided by two Sulzer[1] 1,400 horsepower (1,044 kW) diesel engines and while submerged by two 1,000 horsepower (746 kW) electric motors, allowing speeds of 14 knots (26 km/h; 16 mph) on the surface and 9 knots (17 km/h; 10 mph) while submerged.

[1] In October 1939, Orion moved to Casablanca in French Morocco, from which she conducted patrols in the Atlantic Ocean off the Canary Islands.

[1] On 4 March 1940, Orion sustained a cracked cylinder in one of her diesel engines, forcing her to proceed to Cherbourg, France, for repairs which were not expected to be completed until 1 September 1940.

[1] Disapproving of the desire of some of her crew to join the Free French Naval Forces, Orion′s commanding officer ordered her second-in-command to set an example for them by returning to France to serve the Vichy regime.

[6] Several days later, the second-in-command committed suicide on 25 July 1940 because of stress he experienced over the confrontation between the pro-Vichy and pro-Free France factions of the crew.

To keep the Free French Naval Forces submarines Junon and Minerve operational, she was cannibalized for spare parts.