'Gaff' was a British raid by the Belgian Independent Parachute Company (5^th Special Air Service) and elements of the 1^st and 2^nd Special Air Service against German petrol dumps south of Rouen and also intended to kill Generalfeldmarschall Erwin Rommel at La Roche Guyon in the area of Rambouillet to the south-west of Paris in German-occupied France (18 July/12 August 1944).

In this two-part operation, seven men of the 2^nd Special Air Service with Capitaine Raymond Couraud (J. W. R. Lee) in command were to kill or capture Rommel, the commander of Heeresgruppe 'B' while the rest of the force was to operate against German petrol dumps. The objective of the smaller but potentially more important part of the operation was La Roche Guyon on the Seine river, where the headquarters of Heeresgruppe 'B' was located for the control of the fighting in northern France. Lying up for two days after the arrival by parachute, the seven men of the party received information that Rommel had been injured in an air attack on his car on that day. Lee then decided that his party would operate on foot in this region of the Seine river, and up to 12 August, when it ceased operations before linking up with the advancing American forces just a few days later, the party derailed several trains and destroyed a number of trucks before capping its efforts with an attack on the German headquarters in the town of Mantes, in which 12 German soldiers were killed.

The object of the larger part of the operation was the denial to the Germans of vital petrol and lubricant supplies. The Germans were acutely short of petrol by the middle of 1944, and the Allies fully appreciated that any diminution of the supplies reaching front-line units would have tactical effects highly beneficial to the Allies, so great efforts were made to bomb German oil production facilities, to bomb or otherwise cut the transport routes over which the oil derivatives reached the front, and to destroy dumps and the like.