Giorgio Vasari painted the great east wall of Salone dei 500, illustrating the Florentine victory of the Battle of Marciano, a very bloody battle, where finally Siena fell and Florence became the absolute power in the hands of the Medici family.
On a banner at the top you can read "Cerca Trova" [Search Find]. It seems that Vasari wrote it giving a clue to look for the painting of the Battle of Anghiari by Leonardo da Vinci, which was supposed to be on the same wall, beneath his.
The Florentines, governed by the de'Medici family in 1554, sent the army in the area of Arezzo that had rebelled, stirring up fears in Siena. Siena, which until then had been able to maintain its independence, now feared to be destroyed. Therefore Siena organized a counterattack and, occupied Lucignano and Chiusi, its troops commanded by Piero Strozzi pointed at Marciano, encircling it.
But the Florentines had provided the fortress with a garrison of a thousand troops. The commander of the fortress, Lattanzio Pichi, afraid of being defeated, surrendered to Strozzi. Shortly after, Foiano also fell. The Marquis of Marignano, faithful to the Medici, encamped at the siege of Monte San Savino, went to Marciano to attack Strozzi. On August 1, 1554 the two sides in fighting trim and both with dozens of thousands of men came to fight. The Siena troops were overwhelmed and partly destroyed. This great battle of the 16th century became known as the Battle of Marciano, because of the fortress.
In memory of the great battle that definitely defeated Siena, Cosimo I ordered Bartolomeo Ammannati to build a temple in the place of the victory, and a marble column was erected in Florence, in Piazza S. Felice. Fidelity to Florence was rewarded by giving the permission to insert the same lily of Florence in the municipal coat of arms. Marciano remained under the domain of Florence until 1860.