'Group II' was a US special forces operation to land a 25-man Office of Strategic Services party, all of Greek ethnic origins, on the west coast of German-occupied Greece to aid local resistance forces (18 June/mid-October 1944).

On 18 June a group under the command of 1^st Lieutenant John Giannaris landed on the west coat of Greece opposite Paios island, and in the next two weeks up to 1 July travelled over the mountains to reach its designated base at Papas, some 30 miles (50 km) to the north-west of Lamia.

In the period between 22 and 26 July Giannaris with seven OSS men and nine Andartes (Greek guerrillas) moved 40 miles (65 km) to a forward assembly area in the mountains to the north of Stirfaka. From here the men’s target was a railway crossing protected by a pillbox and a German garrison. The demolitions team moved in and the first train was derailed, and the Germans responded with heavy fire as the party retreated without opening fire. The return to base past German patrols was accomplished successfully.

In the period between 31 July and 3 August, a party of 13 OSS men and eight Andartes left Pappas to the south-south-east, and crossed the Lamia valley to the east of Ipati. On 1 August the party continued to the railway line linking Thessaloníki and Athens. In a night attack the locomotive of a supply train was hit by five rounds of armour-piercing ammunition, and the fire of all available weapons was then played over the train for seven minutes, killing all the German personnel on the train and igniting the wagons, which were loaded with supplies. The US and Greek party withdrew under fire from a nearby pillbox, and was pursued by patrols but returned to base safely.

In the period between 7 and 17 August, a German push into the heights to the north-west of Lamia held by resistance bands was stopped by harassing attacks delivered by the OSS party, British Raiding Support Regiment and Andartes. During the night of 12/13 August Giannaris and his party moved to the south along the heights, descended their eastern side, placed mines on the road beyond one emplacement, and withdrew back to the heights. The leading vehicle of the next convoy to pass was demolished and the area was lit up and strafed. Andarte artillery fire from the mountain top destroyed more German trucks and inflicted more casualties on the Germans.

Between 13 and 17 August another German drive, preceded by artillery fire which caused some Andarte casualties, was met with Andarte artillery fire, which caused many German casualties and destroyed several German trucks, persuading the Germans to call off their attempt to clear the area. However, in those areas which had been overrun by the Germans, towns and villages were left in ruins, and there was much loss of Greek life.

On 20/21 August the OSS party with Colonel West and Captain Frank T. Blanas moved from the Papas base to the railway linking Thessaloníki and Athens at a point some 2 miles (3.2 km) to the north of Kaitna station, and here the area was heavily guarded. The US and Greek party took position just a few yards from the track as the demolition crew placed the charges. Only a few minutes later a supply train approached from the south with a sizeable German guard force. When the locomotive triggered the demolition charges, bazooka rockets burst its boiler and the entire US and Greek party poured fire into the cars. The exchange of fire lasted 15 minutes before all the Germans had been killed or incapacitated. Seven cars were derailed and overturned, and the train was left in flames. The party withdrew under heavy fire and returned to base. Reports listed 80 Germans killed and many more injured.

On 27/28 August a party of six US personnel and a Raiding Support Regiment mortar crew left Papas for a German-held strongpoint in a heavily patrolled area 18 miles (29 km) distant on the railway linking Thessaloníki and Athens, and took up positions 600 to 800 yards (550 to 730 m) from the intended target. As a troop train came within range, the US and British party opened fire: more than 150 3-in (76-mm) mortar bombs were distributed over the train. After several minutes Germans returned fire with heavy machine guns, mortars and a 105-mm (4.13-in) howitzer, and asa large German patrol approached, the attacking party was forced from its positions. The US and British attackers had returned to base by 07.00, and the Germans had suffered more than 85 casualties.

On 30/31 August a US party and a Raiding Support Regiment mortar crew moved 12 miles (19.25 km) from Papas to a location 2 miles (3.2 km) to the north of the Kailsa station on the railway from Athens to Thessaloníki along which the Germans were retreating to the north. In the dark the demolition crew laid its charges, detonated them and withdrew to the heights. The rest of the US and British party waited for the inevitable repair crew, which arrived only at 09.00. When this crew began work, 25 mortar bombs was dropped on it, killing several men and sending the rest scuttling into cover. Some 40 mortar bombs were also dropped on a nearby pillbox and the station. A Panzerzug (armoured train) from Kailsa station opened mortar and machine gun fire, and patrols were dispatched to clear the heights. The US and British party arrived back at base at 18.00.

On 2/3 September a US party and 12 men of the Raiding Support Regiment moved 5 miles (8 km) to the east of their base to the railway at Kaitsa Kalivas station. With their flanks secured, the demolition party laid more than 400 lb (181 kg) of demolition charges along some 2,200 yards (2000 m) of track. When these charges were blown, the track was completely destroyed along with several telegraph communication poles. Evacuation of the German troops, weapons and equipment from southern Greece was seriously delayed, and the repair work now needed brought workmen, rails and protecting troops from other areas. Party withdrew under heavy fire and had returned to base by 10.00.

On 6/7 September a five-man US section of thew operational group made a six-hour march from Papas to the railway connecting Athens and Thessaloníki, but during the night its attempts to lay demolition charges under the rails were discovered by German patrols. The Germans dropped mortar bombs and played machine gun fire over the area for the rest of the night, which diverted attention from other sabotage operations, and the party had returned to base by 07.00.

On 8/9 September the whole operational group and a number of Andartes left Papas for the railway linking Athens and Thessaloníki at a point to the north of Lamia and 2 miles (3.2 km) to the south of Develi. This was a heavily patrolled area which included a pillbox and a German barracks. A reconnaissance of the area had been undertaken by Captain Ford and Corporal Kaleyas. The US plan was for a demolition team to destroy the track after the rest of the operational group had started to attack the Germans at another point, but this was interrupted by German fire at point blank range, which quickly wounded one man. With the German fire increasing, Giannaris ordered a retreat, and while attempting to reach the wounded man detonated a mine and was seriously injured. A corporal moved to within just a few yards of a machine gun and silenced it, allowing the men to withdraw to safer positions and eventually over the mountain top to the rendezvous point. Giannaris was evacuated on 18 September and replaced by 1^st Lieutenant Nicholas Pappas of 'Group III', who assumed command on 25 September.

On 10 September the entire operational group departed from Papas and moved north about 8 miles (12.75 miles) to Dranista, where it was joined by the Raiding Support Regiment unit before the combined units continued to the area 2 miles (3.2 km) to the north of the Kaitsa railway station and occupied an area behind this commanding view over the railway lining lining Athens and Thessaloníki.

At 04.00 on 11 September the Allied force moved to forward positions near the railway station, which was protected by a fully occupied barracks and a pillbox. At 18.00 a long troop and supply train arrived, and the US and British troops opened a heavy fire on this. The railway carriages and wagons were built largely of wood, and the whole train was soon on fire. When the Raiding Support Regiment’s mortar crew had expended all of its bombs, totalling more than 100, and as the arrival of more German troops created a greater threat, the Allied party retreated, reaching the next hill as the area was overrun by hundreds of German soldiers. Even as the Germans continued to illuminate the area with flares and saturate it with machine gun fire for the rest of the night, the Allied party bedded down for the night beyond the area of German attention. At least 100 Germans were killed or injured in the attack. At 09.00 on 12 September the Allied party set off toward for Papas. From that night onward, until they evacuated the area, the Germans fired on these heights before any train passed the area.

At 12.00 on 18 September the whole operational group, Raiding Support Regiment unit and Andartes moved yet again against the railway line linking Athens and Thessaloníki. As the main south/north railway connection in eastern Greece, this was seeing a considerable increase in traffic as the pace of the German withdrawal to the north increased. At 16.00, in broad daylight, with flank security in position, the demolition team placed more than 400 lb (181 kg) of charges. The demolition crew moved out as the charges started to detonate, and the flanking security team also pulled back as machine gun and mortar fire started. The demolition charges destroyed were 1,650 yards (1500 m) of track and a large culvert. By 10.00 on 19 September the Allied party was back at base.

On 6 October most of the operational group, under Pappas’s command and with West as observer, and Andartes guerrilla demolition men set out at 13.00 with four carts disguised as farmer’s carts and drawn by oxen. The party moved to the railway connecting Athens and Thessaloníki at a point 1,000 yards (915 m) to the north-east of Neo Monasterion. The approach to the target was through the flat plain of Thessaly, which offered little in the way of concealment. Close to the railway station were pillboxes, mortars and machine guns. As the demolition party reached the track a German patrol opened fire, pinning it down. Corporal Skiriotis crawled to within 10 yards of the patrol and emptied his sub-machine gun’s magazine, which silenced most of the automatic weapons and allowed the patrol to withdraw. Under 30 minutes of heavy fire from the pillboxes the entire party withdrew safely. By diverting the Germans, two other parties succeeded in blowing the rails. Moving all night, the party reached the rear assembly area at 05.00 on 7 October.

On its fourteenth undertaking, during 10 October the whole US and Greek force was called to an area in which the Germans were in the last stages of their northward evacuation from Athens, in an attempt to prevent the German rearguards from destroying all which they could not remove. The combined US and Greek party reached an area close to the Germans' defensive positions. Iposti had been shelled and the Germans had blown the railway line and bridges between Athens and Lamia, and this prevented the Allied plan from being put into effect, so with its Greek task completed the operational group returned to Paviliani and thence to its Italian base.