In the War of the Third Coalition, Gavasini led a seven battalion brigade in Archduke Charles, Duke of Teschen's Army of Italy. At the time of the Battle of Verona, his unit was assigned to the Left Wing under Paul Davidovich. After a reorganization, he fought in Eugène-Guillaume Argenteau's Reserve at the Battle of Caldiero on 29–31 October 1805. His brigade included four battalions of the "Archduke Rudolf" Infantry Regiment Nr. 16, three battalions of the "Lattermann" Infantry Regiment Nr. 45, and eight squadrons of the "Stipczic" Hussar Regiment Nr. 10.