Thus the Florentines hurried on until they reached their encampment under Serravalle, intending to cross the hill on the following morning.

In the meantime, Castruccio had seized the castle at night, had also moved his army from Montecarlo, and marching from thence at midnight in dead silence, had reached the foot of Serravalle: thus he and the Florentines commenced the ascent of the hill at the same time in the morning.

Castruccio sent forward his infantry by the main road, and a troop of four hundred horsemen by a path on the left towards the castle.

The Florentines sent forward four hundred cavalry ahead of their army which was following, never expecting to find Castruccio in possession of the hill, nor were they aware of his having seized the castle.

Thus it happened that the Florentine horsemen mounting the hill were completely taken by surprise when they discovered the infantry of Castruccio, and so close were they upon it they had scarcely time to pull down their visors.