Not everyone knows, but the genius of Filippo Brunelleschi manifested not only in the construction of the magnificent Dome of Florence Cathedral but also in the fortifications of many inhabited centers of strategic military importance. Moreover, both Vitruvius and Leon Battista Alberti had already emphasized that, in many cases, the architects responsible for the victories were not the commanders who had attacked, but rather the architects who designed the defensive walls that had withstood the assaults!
During these years, the Signoria of Florence commissioned Filippo Brunelleschi to oversee the restructuring of the fortifications in Lastra a Signa and Malmantile, in the Arno Valley under Florence, and in the triangle Castellina-Rencine-Staggia in Chianti on the main road to Siena. The destruction carried out by Castruccio Castracani degli Antelminelli in 1326 in the "Signese" and by the troops of the Visconti in the "Signese" and in the "Chianti triangle" had definitively convinced the Signoria of the need to equip these settlements with defensive systems suitable for true military outposts. These lands thus became permanently "walled," meaning inhabited centers protected by city walls whose construction was planned by the dominant city, Florence, to make them defensive (but also economic and productive) bastions of Florentine domains in the countryside. We will briefly address Brunelleschi as a military architect, where the documentary traces of his presence, although faint, are more readable stylistically and architecturally.
The walls of Malmantile form an almost perfectly rectangular layout despite the undulation of the terrain and the elevated position of the town center. The fortification is equipped with bastions at the four corners and two towers, one in the center of each long side. Via Pisana runs through the length of the defensive system, and it is crowned by the only two gates; at Porta Pisana, the protruding structure is clearly visible, with machicolations interspersed with corbels supporting the walkway, of a type still typically from the 14th century. The use of these architectural elements (as stipulated in the contract), the walls predominantly developed in length and relatively thin and straight, illustrates an archaic and "leaning" military practice, according to which enemies who managed to survive the arrow rain and cross the moat would be definitively routed by pitch, oil, and boiling water poured from the machicolations. This still indicates a fundamental cultural backwardness, both of the various Tuscan cities and of Brunelleschi himself, in approaching a military siege conducted with the new firearms, whose terrible potential was not yet fully known (and exploited). This underlying attitude is also perceptible in the walls of Lastra a Signa, in the protruding structure - without machicolations, probably executed under the supervision of Filippo Brunelleschi - which, despite its intrinsic non-conformity, boasts the merit of being the only one in Tuscany to entirely encircle a late-14th-century urban wall.
The recent attribution of the Oliveto Castle (Castelfiorentino, Florence, 1424) to Brunelleschi's corpus would also indicate a sort of maturation in this sense, with the internal walkway rather than the external, much more effective defensively against the new bombards already in use since the late 14th century. In line with the attribution to Brunelleschi, there would be, at Oliveto, the presence of an architecturally complex and refined element: bricks shaped ad hoc for the construction of corbels. Moreover, he was already preparing to experiment (personally overseeing it) with the potential of brick and its flexibility in building the top five-sixths of the Dome of Santa Maria del Fiore, made of molded and fired bricks using the ancient and codified techniques of Impruneta kilns.
The defensive systems of Staggia (Poggibonsi) were also strengthened a few years later. The castle that has come down to us (included within the city walls), of high medieval origin, is essentially the result of the fortification project implemented by the Franzesi family between the late 13th and early 14th centuries. The city walls are interspersed with square or polygonal towers, and throughout their circuit, corbels composed of three tapered stone drafts towards the base are still visible, intended to support a wooden walkway, except for some corbels with arches in brick, which may indicate the presence of sections of masonry walkway. These corbels represent one of the few and best examples in Tuscany of internal protruding structures (connecting the towers), similar to the solution adopted in the nearby castle of Rencine. It can be hypothesized that only this stylistic trait can be attributed to the reorganization carried out by Filippo Brunelleschi in 1431.
Finally, in Vicopisano, Brunelleschi took on the task of restoring an existing defensive structure, equipping it with a powerful tower with a base located at the level of the fortress's wall walkway (the city walls encircle a hilly area, elevated at its center, on which the fortress and tower stand tall). The works began in January 1436 and concluded four years later, necessitating an inspection by Brunelleschi himself. Connecting the fortress to the Silvatici Tower (one of the towers of the city walls) proved challenging. He accomplished this through a high curtain wall equipped with protruding elements, machicolations, and battlements, which connected to the fortress via a drawbridge, of which only the point of connection to the fortress walls is visible today. This additional wall, lacking arrow slits and crossbow loopholes, would have significantly facilitated and expedited the movement of small contingents and communication between guard posts. Meanwhile, defense operations would primarily be conducted from the Silvatici Tower (the only non-Brunelleschian structure capable of "leaning" defense).
| Thanks to Isabella Tronconi, Expert Florence Guide |
