expedition against Semifonte, for which all these treaties had paved the way. Florence had long contemplated the seizure of that stronghold, for, owing to its strategic advantages and the ease with which the position could be reinforced by friendly neighbours, it had been a thorn in her side. Accordingly the now haughty Republic determined to make an end of it. We have already related how in 1184 Count Alberto had been compelled to accept the same terms exacted from the people of Pogna in 1182--namely, to give his solemn promise to build no defences. Nevertheless, profiting by the arrival of Frederic I. and the difficulties in which Florence was then involved, he had presently erected the Castle of Semifonte on the Petrognano rock, and Florence had never forgiven this offence. He had also assumed the title of _Comes de Summofonte_. Near the castle a town had sprung up, and, as many sought refuge there from neighbouring places conquered and taxed by Florence, its population had rapidly increased. Indeed there was already this rhyme afloat in the _contado_: "Firenze, fatti in là, Che Semifonte si fa città."[214] It was for these reasons that the Republic so persistently tried to secure pledges of help from its neighbours by the numerous treaties to which reference has been made, and likewise by others concluded through the efforts of the energetic Podestà. But Sienna had still to be reckoned with, and Sienna might do good service to the hostile Alberto, who was already prepared for defence. Accordingly the Florentines signed an alliance with that state on March 29, 1201, promising their aid against Montalcino, which showed as threatening a front to Sienna as the Semifonte position towards their own city.[215] Also Colle was made to swear to accord no help to the people of Semifonte.[216] Thereupon the war finally began.