[11] In 1625, when the Republic of Genoa, traditionally an ally of Spain, was occupied by French troops of the Duke of Savoy, the city underwent a hard siege.

[12] However, the Spanish fleet commanded by General Álvaro de Bazán, Marquis of Santa Cruz, came to the aid of Genoa and relieved the city.

In the autumn of 1624, using the pretext that papal forces had not been withdrawn from the Valtelline as agreed, French and Swiss troops invaded the Catholic valleys of the Grey Leagues and seized the forts, to protect them, Richelieu had established the Governors of the Duchy of Milan.

Richelieu hoped England and the Dutch would send a fleet to assist his own squadron in cutting the seaway between Spain and Genoa, while Venice attacked Milan.

[6] Venice abstained from the fighting, while English and Dutch support failed to materialize, enabling Spain to break through the relatively weak French fleet and relieve Genoa in August.

[6] Genoese doge Alessandro Giustiniani wrote: At present our republic and its liberty are founded on its fortunes and on the protection of Spain, and we must hope to find strength in the arms of this monarch.

In March Genoa was attacked by the combined army and the French fleet threatened to cut communications with Spain, capturing three Genoese ships carrying nearly 650,000 pieces of eight.

[19] Above all, Spanish naval superiority would make an effective seaward blockade of Genoa impossible, and greatly reduce the likelihood of success if the siege proved to be lengthy.

[19] At first, Richelieu sought to present the military situation to the king in the most optimistic light, maintaining in May 1625 that: Now all things conspire to cast off the pride of Spain.

Soon the tenacity and experience of the Tercios under the Duke of Feria obtained good results and the French army began to retreat, as they were besieged by two fronts and the situation was becoming unsustainable.

After storming Capriata, Novi and Rossiglione, Lesdiguières decided to slow his pace, capturing Voltaggio and preferring to lay siege to Gavi, against the advice of the Duke of Savoy.

The Duke of Savoy, joined by the Marquis de Créquy, who replaced Lesdiguieres (who had returned to the Dauphiné) beat a retreat to the Piedmont and entrenched their army at Verrua.

[22] The reconquest was brought about that summer and the following autumn by a fleet of forty galleys under the joint command of the republic's general, Emmanuele Garbarino, Spanish admiral Santa Cruz, and the Duke of Tursi.

By October the republic had recuperated all its lost territory with the exception of the castle of La Penna and had even added Oneglia, Ormea, and a number of localities in Piedmont to its possessions.

The reversal of Genoese sorts when all seemed lost, the continued arrival of silver shipments even in Spanish galleys, and the unwavering behavior of Doria and his fellow asentistas de galeras all seemed to substantiate the positions of those who, like Doge Alessandro Giustiani in 1613, saw perfect union and harmony of intents in the alliance with Spain and the bonds between the Genoese nobility and Philip IV.

[24] In March 1626 the French and Spanish concluded the Treaty of Monzón, suspension of fighting between the Duke of Savoy and the Republic of Genoa being an integral part of the agreement.

[6] Abandoned, Savoy was obliged to make its own peace and now sought a Spanish alliance and intrigued with French malcontents against Richelieu, including possible involvement in the Chalais plot to murder the cardinal in 1626.