'Group I' was a US special forces operation to deliver a 23-man Office of Strategic Services party into the Epiros area of German-occupied Greece to aid local resistance forces (23 April/5 September 1944).

The concept of the operational group was based on the belief of William J. Donovan, the creator of the Office of Strategic Services, that the diversity of the ethnic groups in the USA would provide second-generation US soldiers with considerable language facility and who, when grouped into small units and trained to commando standards, could be delivered by sea or air into enemy-occupied territory for harassment purposes and to encourage and support local resistance organisations.

With a Joint Chiefs-of-Staff directive of 23 December 1942, which provided that the OSS should organise 'operational nuclei' for service in enemy-occupied territory, a recruitment programme was launched. Existing line units, officer candidate schools and specialist schools were targeted as pools for candidates who had already received basic training. It was in infantry and engineer units that most operational group candidates were sought, together with signals and medical units for radio operators and medical technicians.

A working knowledge of a foreign language was deemed a priority in the recruiting effort, though candidates with other special skills or foreign area knowledge were also considered for recruitment. Most important were a facility with the French, German, Greek, Italian and Norwegian languages.

Candidates were given the opportunity to volunteer for 'hazardous duty behind enemy lines'. Those expressing interest were interviewed, and possible operational situations were presented to enable the candidate to have an understanding of potential personal dangers. Only men with a real desire for such duty were chosen. About 10% of those interviewed volunteered.

Soon after interview, the selectees received orders to report to OSS headquarters in Washington, DC. After being processed in, most recruits were transported to Area F (the Congressional Country Club in nearby Potomac, Maryland, taken over by the OSS for the war), which served as a base for several different OSS activities. Except for the operational group selectees, most of the personnel went home off base after their day’s work. Apart from a base headquarters unit which included a military police detachment, the operational group selectees were the only military personnel living there.

The golf course was used for operational group training. Special obstacle courses, pistol firing ranges as well as open-air class rooms were located there. Resources such as the Potomac river, the Potomac river locks and other local landmarks and facilities nearby were also fully utilised for operational problems.

Basic operational group training was built on physical conditioning, map reading, night reconnaissance, demolition work, special weapons use and hit-and-run commando tactics, the last incorporating much drawn from the British commando experience. The courses were designed to make all operational group personnel proficient in use of small arms of both US and non-US manufacture; map reading and the use of compass for night operations in scouting, patrolling and reconnaissance; proficiency in the handling and use of demolitions; and living off the land.

During the period of basic training at Area F the formal table of organisation and command assignments of individual operational group units (i.e. French, German, Greek, Italian and Norwegian) were generally completed and designated overseas station assignments established. From that point onward, additional training was more specifically tailored for particular operational needs envisaged for the areas in which they would be working. Some of that training was conducted at other OSS and military facilities in the USA, and some at OSS, military and allied facilities overseas. For example, while all operational group personnel received parachute jump training, those who would be dropped by means of special exit holes cut in the belly of bomber aircraft received extra training. That training was given at OSS parachute training facilities overseas. Some operational group units also received ski or amphibious training.

The basic organisational structure of an operational group section consisted of two officers and 13 other ranks (the enlisted men were all non-commissioned officers). As noted above, all members of the team were equally prepared in weapons and operational skills, and the two specialists were the radio operator and medical technician. The fact that all the men other than the radio operator and medical technician had the same operational capabilities was a major factor enhancing flexibility of assignment and deployment to fit varied mission requirements.

It was at the request of the Greek government-in-exile that the OSS established a Greek operational group from the 122^nd Infantry Battalion at Camp Carson, Colorado, during February 1943. After additions, rejections and further training nearly 200 officers and other ranks was declared ready for foreign duty. In Greece the first armed resistance to the Bulgarian, German and Italian occupations of various parts of Greece came in October 1941, when the first Andartes (Greek guerrillas) came into being in the mountains of Macedonia and then expanded into much of the rest of Greece. As the Allies gained the upper hand in Europe, the withdrawal of the 80,000 German troops in Greece was foreseen, and plans were laid to delay, harass and make this withdrawal as costly as possible. Operational groups and a British unit, the Raider Support Regiment, worked with the resistance movements to accelerate the plans.

The first operational group unit entered Greece on 23 April 1944 as 'Group I' arrived by infantry landing craft from south-eastern Italy with a total of 23 officers and men, mostly of Greek origin and under the command of Captain George W. Verghis, landed near Parga (or Splanza) in Epiros in western Greece with supplies (including dehydrated rations) for 45 days. On this and the next day the group moved to its base, Romanon, a mountain monastery.

By 27 April the group the group was at Glyki working with British and Andartes personnel to close a road related to another landing by infantry landing craft. In the six days centred on 21 May the unit again closed the Glyki road and its successful landing allowed Lieutenant Papazoglou’s group to move into its operational area. In an eight-day period centred on 18 June the road was again closed to facilitate the safe delivery of Lieutenant Giannaris’s group. Another operation followed on the road linking Ioannina and Igumanetsa. High temperatures made life and living conditions very uncomfortable, and several men succumbed to malaria.

On 5/6 July Verghis with part of the group and a number of Andartes ambushed a convoy of five trucks on the road linking Ioannina and Igumaniti, which was the only supply route to Kenkira island. In 40 minutes the trucks carrying personnel, ammunition, mines and fuel were left burning, and only a few Germans escaped. This was the first time Americans struck at Germans in Greece.

On 13 July a 10-day operation to block the at Despotikon began.

On 16 August Lieutenant Paul J. Mackey with part of the group plus part of another unit under Captain Darr, and 150-man battalion of Andartes under the command of Colonel Zotes, used an advance base at Radovici to plan a a siege on Butsara, where there was a 60-man German garrison holding the supplies for the guard posts on the road linking Ioannina and Igumaniti. The approaches were heavily guarded.

On 17 August the party travelled for four hours from Radovici to its selected ambush positions at a horseshoe bend of the road between Vrusina and Menina. Here, at 14.00 on the following day, five trucks loaded with German troops approached from Vrusina. The Germans in the first trucks spotted members of the US and Greek party, and in an exchange of fire several Germans were shot and the rest escaped. In these few minutes, as the trucks turned around, the second turned over, blocking the first, and only the three trucks at the rear of the convoy got away. The two trucks were stripped of all that they carried and then set on fire as the US and Greek party withdrew.

On 25 August, another ambush was established near the horseshoe site, and at 23.00 the lights of 20 to 30 trucks were seen to approach from the west. At this point the Andarte commander withdrew his men, and a few minutes later a long column of 40 or more trucks approached from the east and continued past the smaller column. The tail of the convoy was attacked, eight trucks being destroyed and 30 to 40 Germans being killed or wounded. The OSS party and about 15 Andartes who had had remained with it then returned to Radavisi.

On 28 August it was decided that the condition of the US troops was poor, with only four men fit for duty, and that supplies, including food, had been inadequate.

On 5 September the US party left Greece for Italy. Its mission had been a success at the tactical level, aided the British effort and boosted morale of the Andartes.