'Group IV' was a US special forces operation to parachute a 20-man Office of Strategic Services party into the Thessaloníki area of German-occupied Greece to aid local resistance forces (7 September/9 November 1944).
The OSS party comprised a total of 22 personnel, most of them of Greek origin, under the command of Captain Robert E. Eichler with Lieutenant Paul B. Pope as second in command. The party was flown from Italy to Greece on 7 September in two Douglas C-47 transport aircraft and parachuted into the area of Droma to establish links with local resistance forces and operate against the Bulgarian forces occupying this region of north-eastern Greece. The OSS party was received by four British personnel and 50 Andartes (Greek resistance fighters).
On 11 September the OSS party, aided by two British engineer officers and 12 Andartes destroyed a two-span steel girder railway bridge at Mesokhavan. There were no operations after this until 9 November, for on 13 September the the Bulgarians capitulated to the Allies, and the military objectives for which the operational group could be used were not part of the political turmoil now erupting with still greater violence between the many politically diverse factions which paved to way to the Greek civil war. Eichler considered operations against the Germans in the area to the west of the Struma river, but the Andartes would not assist against the area’s German security battalion, which had been formed from the local population by the Germans, who armed and led them.
On 2 November Captain Houlihan arrived by aeroplane at Droma for final discussion of the situation, and on 9 November the operational group was evacuated via Athens back to Bari in south-eastern Italy.