Task: Question Answering
Input (English): Passage: The irony of a Cardinal attacking the troops of a Pope was not lost on Rome, Spain, and ultra-Catholics in France. In 1625 the French marshals François de Bonne, Duke of Lesdiguières and Charles de Blanchefort, Marquis de Créquy, joined the Duke of Savoy, invaded the territories of the dominion of Genoa. An attack on Genoa would cut the southern end of the Spanish Road and knock out Spain's banker. The time seemed opportune, with the apparent convergence of Protestant hostility to the Habsburgs, and explains French participation in the London talks with Mansfeld. Richelieu hoped Britain and the Dutch would send a fleet to assist his own squadron in cutting the seaway between Spain and Genoa, while Venice attacked Milan. François Annibal d'Estrées, Duke of Estrées and 3,500 French troops crossed Protestant Swiss territory to join a similar number of Rhetians levied with French money. More subsidies and troops poured into Savoy, where the French formed a third of the 30,000-strong army that began operations against Genoa in February 1625. The attack caught the Genoese Republic unprepared. Most of the Republic was overrun, while 4,000 reinforcements from Spain were intercepted by French warships in March. By this time Cardinal Richelieu remarked:. 
Question: How many French marshals joined the Duke of Savoy? 
Answer type: Number 
Output (English): 4.