Troilo II de 'Rossi, Count of San Secondo, was an Italian general of the sixteenth century, the third Marquis of San Secondo and the eighth count of San Secondo.
A member of the Rossi family of San Secondo, he was the son of Pier Maria III de 'Rossi and Camilla Gonzaga, daughter of Giovanni Gonzaga, lord of the Bishop and elder brother of Cardinal Ippolito de' Rossi. Troilo II de 'Rossi, Count of San Secondo, was an Italian general of the sixteenth century, the third Marquis of San Secondo and the eighth count of San Secondo.
On his father's death in 1547 he succeeded him as Count of San Secondo, managing the stormy but uncertain period of the creation of the Duchy of Parma and Piacenza under the Farnese dynasty.
From his father he inherited the title of commander of Italian infantry in the service of the kingdom of France. From the French, openly deployed on the side of the Farnese, he immediately detached himself, even if in the Parma war he did not take a marked position, ending up to join the papal troops with the position of colonel with whom he participated in the siege of Mirandola in 1551.
Joined to the oath of fidelity to Pope Julius III, he repeatedly opposed the pressure of the duke of Parma Ottavio Farnese to act as a vassal to the newborn duchy of Parma and Piacenza, but had to surrender in December 1556 in front of a letter from King Philip II of Spain that ordered Rossi to sell San Secondo ai Farnese.
In the twenty years between 1560 and 1580, after having reconciled with the Farnese, he was at the service of the Duchy of Milan with the rank of cavalry captain and the armies of the King of France, Philip II.
Later he sent troops to Cosimo de Medici, son of Giovanni dalle Bande Nere and a great-uncle of Troilo II to participate in the Siena enterprise, accompanying Cosimo himself in 1570 in Rome when he received from Pope Pius V as Grand Duke of Tuscany.
Troilo II de Rossi is remembered above all for having wanted to embellish and decorate the Rocca di San Secondo, to his will we owe the representations and decorations of the halls of representation and above all the realization and decoration of the hall of the Gesta Rossiane.
Troilo II died on 31 January 1591 and was buried in San Secondo in the Oratory of Santa Caterina inside the Rocca.