'Group III' was a US special forces operation to land a 10-man Office of Strategic Services party, all of Greek ethnic origins, in the north-eastern central part of German-occupied Greece to aid local resistance forces (mid-August/26 October 1944).

Under command of 1^st Lieutenant Michael P. Manusos, the group landed from the sea at Parga cove and marched to Deskharti, some 35 miles (55 km) to the north-west of Larissa.

In its first operation on 20 August, at 04.30, after a four-day march from its base at Deskharti, the party included Manusos, 1^st Lieutenant Nicholas G. Pappas (second in command until he replaced the wounded 1^st Lieutenant John Giannaris of 'Group II' on 25 September), and two Andarte platoons, each with about 22 men, and several British soldiers of the Raiding Support Regiment. The party was positioned for an ambush on the road linking Lakoui and Voube with US personnel in the centre and an Andarte platoon on each flank. At 08.00 four trucks, with machine guns mounted on them, appeared and the engagement began with a bazooka rocket hit from T/5 Peter G. Anton on one truck. The German guns were soon silenced. Within 30 minutes German reinforcements began to arrive from a post at Sarantaporos, and within 40 minutes the arrival of further German reinforcements from Elasson forced the party to withdraw.

On its second operation, the operational group approached two bridges near Kleftherskhori but found these to be too strongly held for any attack to be successful.

On 7 September the operational group left Desokhori at 07.00 and arrived at the rendezvous point, Klisoura, at 21.30. On 8/9 September the operational group moved to reach the town of Likhoudi by 22.00. There followed a reconnaissance of a bridge target before the US party sent out flank protection groups as charges were laid and the bridge blown at 00.15. The group then moved to new rendezvous point at Gavros.

On 10/11 September, after receiving orders to blow the bridges at Klefthesokhori, a reconnaissance party led by a British officer identified wooden bridges, a bypass, pillboxes connected with trenches, surrounding barbed wire fences, minefields and a German garrison estimated at least 50 men. The reconnaissance party was seen and forced to retire under fire, and it was decided that the target was too strongly fortified to be attacked successfully.

On 11/12 September tyre bursters and mines were placed on the road linking Elasson and Kozani on each side of the bridge at Likhoudi by 03.45. The mines subsequently destroyed at least 15 trucks and the Germans were delayed for a day and a half.

On its fifth operation, the party was again strengthened by Andartes and on 24 September moved from Desokhori to its target, the road linking Tirnavos and Elasson. This was built into the side of a mountain with high supporting walls. As there was no sign of any German presence, during the night of 25/26 September holes were dug, explosives placed and the road blown, After which time-fused bombs, tyre bursters and mines were placed. The road and walls were completely destroyed and made unserviceable for 10 days, and 12 trucks were destroyed and 80 Germans killed or wounded by Andarte fire from surrounding hills.

The sixth operation, on 27/28 September, was an attempt to blow another bridge, but this could not be completed because the party had insufficient explosives.

On 2/5 October, in its seventh operation, the operational group, again with Andarte and British support, moved to destroy 200 parked trucks, being used for the German evacuation, but the undertaking was not completed because of the apparent reluctance of Andartes to co-operate in obtaining the mules which were needed and the Germans then moved the convoy.

The eight operation was to use the operational group, Andartes and British personnel to blow bridge and lay mines on the load linking Elasson and Servia, but was delayed for three days and finally cancelled as the party watched a continuous caravan of heavily protected evacuating German vehicles.

Between 9 and 26 October the combined US, Andarte and British forces attempted four largely ineffectual operations as they tracked the German forces evacuating Greece along the routes from Tricala northward to Grevena. Contact was then made with an advance party of British troops from Lamia.