Collegno fought during the Napoleonic Wars, reaching the rank of colonel in an engineering unit. Following his exile from Italy he joined his friend count Annibale Santorre di Rossi de Pomarolo, Count of Santarosa to Greece where they fought in the Greek War of Independence. On 31 March 1825, he was appointed head engineer of the Neokastro garrison which at the time was undergoing a siege by Egyptian troops.