Julius II, having secured his own control of the Papal armies by arresting and imprisoning Cesare, first in Bologna and later in Ravenna, quickly moved to re-establish Papal control over the Romagna by demanding that Venice return the cities she had seized. The Republic of Venice, although willing to acknowledge Papal sovereignty over these port cities along the Adriatic coast and willing to pay Julius II an annual tribute, refused to surrender the cities themselves. In response, Julius concluded an alliance with France and the Holy Roman Empire against Venice; the death of Isabella I of Castile and the resulting collapse of relations between the parties soon dissolved the alliance, but not before Venice had been induced to abandon several of the cities. Julius, although unsatisfied with his gains, did not himself possess sufficient forces to fight the Republic; for the next two years he instead occupied himself with the reconquest of Bologna and Perugia, which, located between Papal and Venetian territory, had in the meantime assumed a status of quasi-independence.