Della Somaglia was born in Piacenza in 1744 to Count Carlo Maria Cavazzia and Countess Marianna Fenaroli; he was one of five children.

[1] He was sent to Rome at the age of twelve and studied at the Collegio Nazzareno and La Sapienza University, acquiring degrees in both canon and civil law.

[1] In his years as a cardinal della Somaglia played an important role as a negotiator with the revolutionary regime in France.

Although he undoubtedly agreed with Pius VI's 1791 condemnation of the French Revolution and was expelled from Rome when Napoleon's army invaded in 1808, he was charged with the examination of the concordat with France several years later.

This role served to taint della Somaglia's reputation in the eyes of fellow zelanti cardinals.