On May 18th, General Béthencourt arrived at the edge of a precipice which was usually crossed on pieces of wood, one end of which rested in the hollowed-out rock, and the other on a beam across it. This sort of bridge had been swept away by a rock splinter, and carried off into the current that flowed along the edge of the abyss. Only the row of holes remained, into which one end of each piece of wood had been inserted: one of the boldest soldiers offered to put both feet in the first two holes, then to stretch a rope at head height, walking from cavity to cavity, and when he had managed to secure the rope to the other end of the gap completely empty above the abyss, General Béthencourt set an example of crossing thus suspended by his arms on even a very thin rope; And so it was that a thousand Frenchmen crossed a gap an interval of ten fathoms, laden with their weapons and packs. Once the crossing was completed, the name of General Béthencourt and the officers of the general staff were engraved on the rock.

Beautés des victoires et conquêtes des Français, depuis 1792 jusqu'en 1815 : récit des campagnes de la Révolution et de l'Empire, beaux faits d'armes et de dévouement des soldats français. Tome 2 / par E. de La Bédollière, 1847.

Gallica

Simplon Pass and Reflections, 1960s

Simplon Pass - Switzerland (by Anna Jewels (@earthpeek))