The Royal Air Force Special Duties (SD) Service was a secret air service created to provide air transport to support the resistance movement in Axis controlled territories. The service helped develop and support the resistance by bringing in agents, wireless operators and supplies. Parachute drop was the primary method by which the Special Duties units delivered supplies and most of the agents to the occupied countries. They also developed an air taxi service to pick up agents, political leaders and special communications from occupied Europe and bring them to England. On the outward flight the air taxi service also delivered agents and high value packages to France. Special Duties flights flew to target fields in Vichy France, Occupied France, Belgium, Netherlands, Norway, Poland, Czechos