During the peace, Fririon commanded the troops in the Bas-Rhin department. He later fought under Marshal André Masséna in Italy. He served at the Siege of Stralsund which lasted from 15 January to 20 August 1807, when the Swedish garrison abandoned the city. On 25 August he and French naval Captain Montcabrié attacked the fortified island of Dänholm between Stralsund and Rügen. The 1,200-man French force included one battalion of the 30th Light Infantry Regiment, two artillery pieces and crews, and detachments of sappers, miners, and Sailors of the Imperial Guard. The operation was a success, costing the French only 15 dead and 26 wounded. The 900-man Swedish garrison lost 50 killed, 75 wounded, and 517 captured. Six field pieces and eight heavy cannons also fell into French hands. The following year found him serving under Marshal Jean-Baptiste Bernadotte in Denmark. He was present during the mutiny of two Spanish regiments on 31 July 1808, during which his aide was killed. The mutiny was suppressed the next day by a superior force of Danish troops. However, most of the other units of the Spanish Northern Division escaped in British vessels during the evacuation of the La Romana Division.