As nationalism swept the Italian Peninsula in the 19th century, efforts to unify Italy were blocked in part by the Papal States, which ran through the middle of the peninsula and included the ancient capital of Rome. The Papal States were able to fend off efforts to conquer them largely through the pope's influence over the leaders of stronger European powers such as France and Austria. When Italian troops entered Rome, the Italian government reportedly intended to let the pope keep the part of Rome on the Vatican hill west of the Tiber, called Leonine City due to its walls built by Pope Leo IV, a small remaining Papal State, but Pius IX refused. One week after entering Rome, the Italian troops had taken the entire city save for the territories of Vatican Hill; the inhabitants of Rome then voted to join Italy (those living in the Vatican were allowed to vote outside of the Leonine walls).