In 1799, he commanded a division of the French
Army of Helvetia in Switzerland under Massena's command. At the outbreak of the campaign, he covered the left wing, with responsibility for the invasion of the
Grisons, with two brigades under command of
Nicolas Oudinot and Ruby. This wing was to maintain communication with the
Army of the Danube via Ruby's brigade, which stood at the farthest left, in the vicinity of
Schaffhausen. Throughout that summer, he was instructed to observe (and report) all Austrian movements near along the Rhine and
Lake Constance. As the Austrian army, 30,000 men in the Tyrol, 28,000 on the line between
Vorarlberg to
Bregenz, and 40,000 around Lake Constance, threatened all French communication and the best lines of retreat. Ruby's brigade by Schaffhausen was the best, and sole, protection for any retreat, if necessary. By April Massena had prepared his plans, and reorganized his nine divisions into four corps. Xaintrailles covered the left wing, with the divisions of
Souham and
Legrand, 18,000 men in all. This wing spread in the direction of the Rhine, where Souham's force covered Frickthal and Basel, between the
Aare and Hüningen, and Legrand's brigade held
Altbreisach and
Kehl, and observed the debouches from the Black Forest. A division of heavy cavalry reserve also occupied
Basel. In addition, Massena sent Xaintrailles to
Valais, with 6,000 men, where some of the inhabitants had mounted an insurgency against the republican forms adopted by the new Swiss government. Xaintrailles originally positioned himself in
Solothurn, but Massena instructed him to proceed further south, to the heart of the insurgency. This placed him at the farthest right of the French line where he could defend the
Simplon Pass and
Great St Bernard Pass against Habsburg troops in northern Italy.
Valais insurgency On 24 May 1799, several thousand insurgents, reinforced with French deserters, recruits from some of the minor cantons, some Austrian battalions, and emboldened with the news of approaching Russian forces, emerged from the wood at Finge and attacked Xaintrailles' encampment. The French beat them off and they withdrew to their own entrenchments. Before daybreak on the following morning (25 May), Xaintrailles attacked in two columns. The first, Column Barbier (three battalions and one squadron), drove the insurgents out of the woods and chased them to the
Leuk. The second, the left column, including two battalions of the 89th and 110th as well as some of the grenadiers of those two demi-brigades, were under the personal command of Xaintrailles, and attacked the insurgent position at Leuk, defended by seven guns so carefully placed as to deliver
enfilade fire on the passage of the valley; furthermore, the insurgents had placed sharpshooters on the approaches to the gorge. Xaintrailles sent two flanking detachments to the crest of the mountains, well out of artillery range, while the main body in the valley attacked the position in front of them. It received such a storm of musketry and canister fire at the foot of the entrenchments that it began to waver; at this point, a well-sustained
fusilade from the crest of the mountains showered the insurgents' flanks. The men in the gorge redoubled their efforts and entered the Valais entrenchments, slaying some of the gunners at their positions. The survivors fled to
Raron, abandoning their guns and magazines. On 26 May, Xaintrailles' right column crossed the
Saltina river via a ford and marched to
Brig, where some of the insurgents had rallied. These abandoned the town and fled into the mountains behind it. The left column, column Xaintrailles, reached
Naters on the right bank of the
Rhône and proceeded to
Mörel and
Lax, seeking to capture the bridge between Lax and
Ernen, where the largest group of the insurgents had congregated. While he was reforming his troops, he offered the insurgents an olive branch: if they would lay down their arms and return to their homes, he promised an amnesty for the past. Those who persisted in revolt would face
summary execution. A number of the insurgents did submit, but many withdrew to Lax where, reinforced by a couple of Austrian battalions, they rejected all offers of amnesty and placed their reliance on nature's formidable position. There followed a day-long battle with alternating results; eventually, the insurgents were routed, but the contest was maintained by those two Austrian battalions, who eventually abandoned the field as night fell, and light failed. Xaintrailles pushed on with the grenadiers of the 100th and sent several companies of the 100th to St. Bernard. His Swiss allies guarded the gorges and defiles behind him. He established his headquarters at Brig, from which he could control the passes at Great St. Bernard and Simplon and access to northern Italy, and awaited his instructions from Massena. ==Excesses==