Knowing he was outnumbered, Derby waited near Périgueux for several days for the arrival of a force under the Earl of Pembroke. Unknown to Derby, another French army of some 9,000 to 10,000 men under the Duke of Normandy was only away. On the evening of 20 October Derby decided that waiting any longer would invite an attack from the larger French army and made a night march, crossing the shallow river twice, so that by morning he was situated on a low wooded hill about a mile (1.6 km) from the main French camp in the valley by the river. Derby personally reconnoitred the French position. Still hoping for the last-minute arrival of Pembroke, Derby called a council of his officers. It was decided that rather than wait and possibly lose the advantage of surprise, the army would attack immediately and attempt to overrun the French camp before an effective defence could be devised.