One of the transformers destroyed during the attack (German Federal Archives)
In late May 1941 the Special Operations Executive (SOE) received a request to sabotage the power station in Passaic near Bordeaux but due to other operations they had no agents available and asked the Polish Section (EU/P) which came under the jurisdiction of the Polish Government in Exile in London whether they would be take the mission and after agreeing six Polish volunteers boarded an RAF aircraft of 138 Special Duty Squadron at RAF Tempsford to parachute into France.
Shortly after entering French air space the aircraft suffered an electrical fault which caused their container loaded with weapons and explosives to be jettisoned over the Loir and were forced to abandon the mission and return to England. Unbeknown to the aircrew the electrical fault was serious and caused the aircraft to crash land at Tempsford and catch fire: all the crew were either killed or injured and the six Polish agents suffered serious burns.
SOE HQ then asked RF Section (the Free French equivalent to SOE under General de Gaulle) whether they were willing to attack the power station and after de Gaulle agreed, on the night of 11-12 May 1941 three agents from RF Section, J Forman, Raymond Cobard and André Vernier (aka Jacques Leblanc) successfully infiltrated France by parachute.
After hiding their weapons and explosives the team reconnoitred the power station: there was a high-tension cable very close to the top of a 9-foot wall they needed to climb over and it appeared there was a large number of German and Italian soldiers protecting the power station. They also failed to obtain the bicycles which they intended to use for the getaway so decided to postpone the attack.
Before leaving England Forman was given the Paris address of an RF agent named Joêl Letac who remained in France after a failed mission called Operation Savanna and after meeting Forman Letac rallied that team and encouraged them to continue the mission and the following day travelled with them to the power station. After the old lorry they obtained broke down they continued the remainder of the journey on stolen bicycles and recovered the equipment they had buried around 100 yards from the power station.
On the night of 7-8 June 1941 during pitched darkness due to the blackout Forman climbed the perimeter wall and crawled under the high-tension cable which was dangerously close. After ensuring he could not be seen by the guards Forman entered the compound and opened a side door, the rest of the team entered the grounds of the power station and then sprinted across open ground to the main building.
In less than thirty minutes the team placed magnetic incendiary devices on eight large electricity transformers and then made their getaway on the stolen bicycles. It has been said the explosions were so violent flames rose high into the air and illuminated the entire area as searchlights started probing the sky for bombers.
Six of the transformers were destroyed and this seriously disrupted the the Bordeaux submarine base, numerous factories used to supply the German army were forced to stop production for several weeks.The electricity grid from another region was diverted but the overload caused more damage and all electric trains in south wester France had to be replaced with steam locomotives, and all the transformer oil in France had to be used during the repairs.
Some writers claim the team was picked up by an RAF Lysander of 161 Special Duty Squadron, but this was not the case. The team arrived in France with one million francs (said to be about £1,400 in 1941 and roughly £71,000 in 2021) and the money was unaccountable! Instead of requesting an extraction they remained in France for a further two months and according to historian MRD Foot “They left behind them broken glass and broken hearts” before making for neutral Spain and arriving back in England. Before crossing the frontier Cabard was captured but later escaped and returned to England.