Historical fact.
Between April and May of 1260, the powerful and victorious army began a Florentine
military campaign in the territory of Siena .
The large army , formed by the militia and infantry -sixths of all citizens and the countryside , and flanked by the contingents of the allied cities , had been prepared to bring aid to the Castle of Montemassi ( Maremma ) under siege by the Sienese, defended by Aldobrandino Count of Pitigliano and a garrison of " sergeants " Florentine .
The massive amount of men and animals ( some modern estimates speak of only 15,000 individuals from Florence and its suburbs ) " made ​​the move " on April 19 from Florence with the intention, not only to help the ally castle , but give a show of strength to the rival city .
Just arrived within the borders of the Committee of Siena, and conquered the castles of Casole d' Elsa and Mensano , the command Florentine decided to abandon the initial target ( the Count Aldobrandino and sergeants Florentines , apparently , if they were faring well) for point directly over Siena.

The camp Verniano :
Removed from the field Mensano , then pointed at Verniano , where they camped in the days of May 6 and 7 , then Abbey Island , near Monteriggioni and so took the path that leads to the northern walls of Siena.
Just at the entrance of the "city of the sock " , near Santa Petronilla ( current Antiporto Camollia ) , the Florentines took sides with the intent to mock the Sienese , and maybe ask them out .
" It is said that a contingent of several hundred German knights ( teotonichos ) , sent by King Manfred to reinforce the Sienese militia , led a sortie that led to the feat of arms now known as the " Battle of Santa Petronilla " fought the 17th day of May 1260.
Like many aspects of this story , this clash is shrouded by the mists of myth and heroic tradition . The outcome , in reality, is uncertain. The fact is that the Florentines returned home victorious and happy to have captured German prisoners , and even an imperial flag (at least so goes the story ) . The Sienese , on their own, declared themselves winners for breaking the siege.
This military campaign preceded by a few months, the far more famous Florentine expedition to the rescue of Montalcino , which ended disastrously with the Battle of Montaperti .