Pas-du-Roc artillery work main armament consistedof two 75mm guns and four 81mm mortars.
Its mission was to block the Fréjus Valley and cover the Fréjus, Arrondaz, Fontaine-Froide and Vallée-Etroite passes.
The garrison comprised 5 officers and 167 men from 164 Position Artillery Regiment, 81 Fortress Alpine Battalion, 4 and 28 Engineers Regiment. Captain Chanson of 4 Engineers Regiment commanded the fort.
On the morning of 21 June, the fortress was shelled by Italian artillery. At around 1 p.m., Italian 3 Battalion, 91 Infantry Regiment crossed the Fréjus Pass and advanced into the valley. The mortars of the Pas-du-Roc stopped them. At 1.42 p.m., block 4 opened fire on machine guns harassing Fréjus work.
On 22 June, the structure was shelled, damaging the cable of the telpher carrier.
On 23 June, Italian artillery targeted the structure, without success.
On 24 June, at 4.30 a.m., Italians reached the upper external structure. The mortars of Lavoir opened fire on the superstructure of Pas-du-Roc. The twinned machine-gun from Block 1 swept the neighbouring slopes, then Lieutenant Baccard and volunteers went out to inspect the surrounding area without finding any traces.
At 7.30 p.m., the structure fired to clear Arrondaz and Fréjus structures.
From 10 p.m. to 12.15 a.m., block 3 fired on Italian gatherings in the Saracens Massif sector.