The storming of the fortress near Porta Camollia in Siena

Vasari's fresco of the Storming of the Fortress near Porta Camollia in Siena, executed in 1570, celebrates one of Cosimo I de' Medici's most significant military achievements: the conquest of Siena in 1555, which completed his project of bringing all Tuscany under Florentine dominion. Porta Camollia was the northern gate of Siena, and the assault on its defensive fortifications was among the decisive engagements of the final siege. The fresco's date of 1570 — fifteen years after the actual event — demonstrates Cosimo's continued desire to memorialise his military conquests in the Palazzo Vecchio's visual programme. Vasari, working in his most assured late manner, brought to this subject the full compositional power he had developed through decades of battle fresco painting, creating a dynamic scene that combined historical documentary detail with dramatic pictorial invention.

The late fresco technique shows Vasari's most confident and economical handling — large, clearly articulated forms, decisive tonal contrasts, and the experienced orchestration of a complex assault composition. Siege warfare offered visual elements — walls, defenders, attackers, ladders, cannons — that Vasari organised into a legible narrative of escalating military action.