In 1941 he was seconded to Special Operations, War Office, in 1941. On 28 May 1943 he has parachuted into highlands of Montenegro as representative of the British GHQ in the Middle East to the central command of the Yugoslav Partisans, who were led by Josip Broz Tito. Deakin's mission, codenamed "Typical", joined Tito as the partisans were being hunted through the mountainous ravines of the region surrounding Mount Durmitor by German and Italian forces during operation Schwarz. Just below the summit of Mount Ozren, the partisans were trapped by German aerial bombardment and forced to take cover among birch groves. In one attack, a cluster of bombs fell among them, killing Deakin's radio operator, Bill Stuart, Tito's Alsatian dog 'Luks', and wounding both Tito and Deakin.