Here's what happened in the "Stray Dogs" episode of "The Borgias":
The episode opens with the Pope congratulating Cesare and Vittorio on their brilliant deception of the French forces. But the mood is quickly shattered: Micheletto brings Cesare word that the convent of St. Cecilia has been targeted by the retreating french forces. Cesare rides there and finds Ursula dead: "She chose God, and God repaid her with mutilation...she has released my heart of all emotions save one," he says, vowing to get revenge.
Cesare orders Micheletto to round up a dozen of men like him: "stray dogs," men who would do vengeance in the Borgia name. Just when you thought Micheletto couldn't get any cooler, he's training a mini-army of assassins. Cesare, Micheletto, and the dirty dozen attack a squadron of French scouts with an amazing array of weapons: the paso doble, the raven's beak, the trident.
Meanwhile, several men (including Ludovico Sforza and Gonzaga) have approached the Pope about forming a league of the Italian states to eject France once and for all. Interestingly, the Duchessa Bianca, the new-minted bride to Gonzaga, is the girl who was in the tub with the Pope in the season opener.
The league is a good move for Rome, not only to get rid of the French, but to prevent future in-fighting in Italy that could affect him. If the two sides batter each other to death, that creates a weak Milan, weak Venice, weak Mantua, and a weak France. Rome's enemies can lick their own wounds for a while and leave the Borgias alone.
With the Pope away from Rome to consult with the League, he leaves Lucrezia on the Papal throne. She uses that leverage to further her plan with Giulia to ensure that the poor get the funds earmarked for them, and to restore fresh running water to the populace.
Micheletto's torture of captured French soldiers reveals that the powder for the French cannon travels disguised in the kitchen wagon as food. The French armies and the armies of the Italian league are set to fight. While the Pope spends the night before battle in the arms of the Duchessa, praying for rain to dampen the powder, Cesare takes matters into his own hands. After he and his men lay fiery waste to the French camp, the rain does come, and puts the fire out.
Who really has the family's best interests at heart? The pope is content to pray and indulge in sins of the flesh, while Cesare does all the actual work required to protect his family.