This was a US special forces operation to parachute an Office of Strategic Services operational group into the Devesset area of German-occupied France to aid local resistance forces in the harassment of the German lines of communication in the area and to co-ordinate operational group undertakings on the western side of the Rhône river (24 August/4 September 1944).
Commanded by Major A. T. Cox, the eight-man 'Lehigh' group was the tenth of the 12 such groups parachuted into France from the OSS base in North Africa. At 20.00 on 24 August the group departed the airfield at Blida in Algeria in an adapted Short Stirling bomber and headed for the 'Tandem' drop zone near Devesset in the Ardèche département in the Rhône-Alpes region of south central France. The flight was uneventful and the group’s drop was made on 25 August onto a pasture where the resistance reception party was waiting to take the group to accommodation and food in Devesset.
On 25 August Cox contacted Commandant Vanel, the head of the Ardèche unit of the Forces Françaises de l’Intérieur (French forces of the interior) resistance organisation. The French believed that main routes used by Germans as they pulled back from the south of France after 'Dragoon' were the west bank highway of the Rhône river valley and the east/west highways to the south of the Ardèche, generally in the line lining Villefort, Vallon and Privas line. The French knew that the rest of the Ardèche had been liberated.
Cox and Vanel travelled to Vals les Bain to meet other resistance leaders and 1st Lieutenant W. H. McKenzie, the leader of the 'Louise' operational group, which had arrived on 18 July, to settle points of dispute. Then at Chapelle sous Aubenas Cox visited the section of the 'Louise' group immediately after the ambush and firefight earlier on the same day when the resistance force had pulled back, leaving the operational group section to fight its way out of the trap.
Cox then returned to Vals les Bains and recommended to Vanel that the operational groups be assigned to sectors where the resistance forces had revealed good leadership, discipline and combat activity, that sectors be required to maintain proper liaison with adjacent sectors, and that a central reserve of weapons, ammunition and men should be established to allow rapid reinforcement of threatened sectors.
On 27 August, after the resistance reported a major German column heading to the north near Tournon along the western side of the Rhône river, Cox moved out with a number of men , met the resistance advance guard and took cover off the road, although not before being sighted and coming under fire. The detail returned to the base at Devesset on the following morning and reported the column’s movement to Algiers as well as the headquarters of the resistance. The 'Lehigh' group later learned of the destruction of about 50 vehicles of the 50,000-man German column which had passed through Tournon on its way to Lyon over a period of four days and nights. However, at least 1,000 vehicles got through.
On 29 August, Cox reconnoitred the Vals les Bains area with Vanel and the local FFI leaders, after which commented that there was too much discussion but not enough orders, that the selection of positions was made from road maps and there was little or no appreciation of the terrain, and that in general the standard tactic was to place one company on every road, theoretically surrounding the the Germans, though the reality was that Germans selected the route they wished to use, blasted their way through the one company covering it, often just by the display of firepower, and the utility of the other FFI companies was this wholly wasted.
One the other hand, Cox added, much good work was being achieved by small groups operating in true guerrilla fashion, hitting and running as they made repeated slashing attacks on the German flanks, and that as the success of the Allied armies became more certain, the FFI’s strength grew enormously and the FFI units had begun to think of themselves as an army rather than as a large number of guerrilla bands. However, the FFI lacked the weapons, discipline and leadership which would have allowed them to fight pitched battles against trained combat troops, and increasingly great attention was paid to projects such as the liberation of Lyon and other large cities at the expense of the continued harassment of German columns.
During the four days in which the large German column passed through Tournon, Cox continually urged the FFI to concentrate all available forces on hitting this column repeatedly. However, the FFI’s higher command echelons ordered the concentration of all possible Ardèche groups farther to the north to aid an attack on Lyon. The German column therefore had to brush aside very little opposition before reaching Lyon, where they blew the bridges and withdrew completely. On the following morning the FFI triumphantly 'liberated' the city. This procedure was typical of many such 'liberations'. Thus, Cox observed, the Germans generally held what they wanted, and only after they had left did the FFI moved in.
On 31 August Cox and his group observed the German column as it continued to move to the north. Returning to Devesset, Cox received an instruction to go to Chaumerac and assist in the surrender of a German column. When he arrived the surrender had taken place, but he participated in subsequent interrogations and the internment of the surrendered Germans as the French 1st Division Blindé moved to the north through the Ardèche.
On 2 September, at Yzeron near St Etienne, Cox made arrangements for the advance on Lyon were with the 'Louise' and 'Helen' groups as well as the FFI. During the early morning of the next day, Cox and his group set off Lyon and met Captain L. Vanoncini who, with some of his 'Helen' group, was spearheading the approach, and who went on with a detachment of the French army to see about holding a bridge. Cox and several members of his 'Lehigh' group, proceeding on foot, somehow got in front of the FFI, which were still forming up, and had to fight through wildly cheering crowds. From the cathedral the Americans then watched the arrival on the river bank of the French army and FFI units as there erupted a mass of wild weapons fire which resulted in a number of casualties, civilians everywhere hugging and kissing with complete disregard of the weapons fire, and members of the Milice Vichy French para-military police hunted down and killed.
In the afternoon Cox contacted Major General John E. Dahlquist, commander of the 36th Division on the eastern side of the Rhône river, informed him what he knew of the German and French armies, and offered any possible assistance. Between 4 and 9 September, arrangements were made for assembling all the operation groups, their tasks completed, at Grenoble.