Guieu commanded a brigade in
Jean Sérurier's division during the
Montenotte Campaign in April 1796. During the action at
San Michele Mondovi on 19 April, his brigade flanked the
Sardinians out of position, though the Sardinians later drove the French back when they dispersed to plunder the village. During the
Battle of Mondovì on 21 April, Guieu's brigade played a prominent role and helped capture the village of
Vicoforte. During the first
Austrian attempt to relieve the
Siege of Mantua, Guieu led a brigade in
Pierre Sauret's division. Surprised by the attack of
Peter Ott on 29 July, Guieu rallied 400 men and withdrew to the Palazzo Martinengo in the village of
Salò. Though without food, Guieu withstood a siege by
Joseph Ocskay's brigade until the 31st, when Sauret drove the Austrians away after a sharp action. During the
Battle of Lonato on 3 August, Guieu led Sauret's division when the latter was injured. He recaptured Salò and attacked
Gavardo from the east. Though driven back on Salò, he held his ground. The presence of a French division so close to the Austrian line of retreat helped
Peter Quasdanovich make up his mind to withdraw in the early hours of 4 August. On the first day of the
Battle of Arcola, Bonaparte ordered Guieu to take the 18th and 25th Demi-Brigades across the
Adige River at a ferry near
Albaredo d'Adige. Guieu successfully carried out this assignment and drove the Austrians out of
Arcole late on the evening of 15 November. Bonaparte later withdrew the troops and the village had to be fought over on the following two days. On 6 December, Guieu received promotion to
general of division. In March 1797, he led a division in driving the Austrian army out of northeast Italy, fighting at
Sacile and seizing
Palmanova. He helped
André Masséna and Sérurier trap the division of
Adam Bajalics near
Tarvisio. ==Later career==