These developments emerged most dramatically as the Greek Resistance announced its presence to the world with one of the war's most spectacular sabotage acts, the blowing up of the Gorgopotamos railway bridge, linking northern and southern Greece, on 25 November 1942. This operation was the result of British mediation between ELAS and EDES (Operation "Harling"), carried out by 12 British Special Operations Executive (SOE) saboteurs and a joint ELAS-EDES force. This was the first and last time that the two major Resistance groups would cooperate, due to the rapidly developing rivalry and ideological retrenchment between them.