Having subdued Austria and created the Confederation of the Rhine, Napoleon was determined to crush the remnants of the Prussian army, most of whom had been killed or captured in autumn 1806. Napoleon followed the Prussians as they moved eastwards, punching his way through Prussia in less than three weeks. After successfully capturing Berlin and Warsaw, he attempted to trap mobilized Russian forces at Pultusk. The Russians escaped to the east and, as winter set in, Napoleon grounded his forces. The campaign was accidentally revived under French commander Marshall Ney when, in search of supplies, he came up against a larger Russian force moving westwards. Napoleon was forced to order his army back into the field where they engaged in combat with the Russians at Eylau, towards the north. After a brutal clash and heavy losses on both sides, the Russians, despite belated Prussian support, retreated.