In the spring of 1249, a Guelph Romagnol army of the Lombard League advanced to the Panaro. The army was composed of 3,000 Knights and 2,000 foot soldiers from the Margrave Azzo VII d'Este and 1,000 Knights and 800 foot soldiers of Bolognese militias from Porta Stieri, Porta San Procolo and Porta Ravegnana. The army was led by the Brescian Filippo Ugoni, who had victoriously defended Milan while besieged by Emperor Frederick II, and accompanied by Ottaviano degli Ubaldini, the Cardinal of Bologna.
The Guelph army threatened the Ghibelline city of Modena and therefore the Modenese had requested help from Enzio of Sardinia, who was then imperial vicar in northern Italy, and resided at Cremona.
Enzio organised a massive army of 15,000 men, composed of Imperial Germans and Lombard Ghibellines from Cremona and Modena. He led the army across the Po by using his self-constructed bridge at Bugno. They arrived at the Fossalta stream, some 5 km north of Modena.