 Complete the following phrase:  As Maclean was preparing for the return journey, an urgent signal arrived from Vivian Street stating that on 25 May there had been a large-scale airborne attack on Partisan HQ with gliders and parachute troops, that the Partisans had suffered heavy casualties and that Tito and the Allies missions had managed to escape capture. Unbeknown to him, a meticulously planned and executed 