Coll. Gpe mémoire du pays Bellegardien
From 17 June, the western approaches to the fort were controlled by a detachment of 179 Fortress Alpine Battalion (BAF), holding a fortified strongpoint at Longeray, located in front of the fort and supported by its artillery.
Mission was to prevent access to the fort, the tunnel and the Longeray viaduct crossing the Rhône.
Another detachment was positioned on the left bank, opposite the fort, holding the openings of the tunnel and the Longeray viaduct over the Rhône.
On the morning of 22nd, a German reconnaissance party arrived opposite the strongpoint, triggering friendly fire forcing it to retreat to Léaz.
Reinforced by motorized means, they tried again to overrun the strongpoint. The defenders repelled the enemy, who had to withdraw with heavy losses, pursued by artillery fire from the fort.
On 23rd, large German tracked reinforcements regrouped at Léaz, with a view to resume the attack on Longeray, but were dispersed by the fort artillery, causing significant damages and heavy losses.
Given the size of the German forces and the risk of being overrun, the defenders withdrew to the upper fort on the afternoon of 23rd.
The evacuation of Longeray hamlet paved the way for German advance, since the fort had no longer cover on the left bank, the two Alpine battalions of 230 Demi-Brigade having withdrawn to reinforce the defense of the Italian border.