At Landshut he gave his army two days' rest; wrote and sent a paper to his brother Prince Henry, who was commander of the army defending Saxony from invasion, telling him that he was on the point of marching against the Russians and might well be killed; and giving him orders as to the course to be pursued, in such an event.
He left Keith, in command of forty thousand men, to hold Daun in check should the latter advance against Silesia; and he again took Fergus with him, finding the young officer's talk a pleasant means of taking his mind off the troubles that beset him.
In nine days the army, which was but fifteen thousand strong, marched from Landshut to Frankfort-on-Oder.

Here the king learned that though Kuestrin, which the Russians were besieging, still held out, the town had been barbarously destroyed by the enemy.
In fierce anger the army pressed forward.

The Russian army itself, officers and men, were indignant in the extreme at the brutalities committed by the Cossacks, but were powerless to restrain them; for indeed these ruffians did not hesitate to attack and kill any officer who ventured to interfere between them and their victims.
The next morning, early, Frederick reached the camp of his general Dohna; who had been watching, although unable to interfere with the Russians' proceedings.

The king had a profound contempt for the Russians, in spite of the warning of Keith, who had served with them, that they were far better soldiers than they appeared to be; and he anticipated a very easy victory over them.
Early on the 22nd of August the army from Frankfort arrived.
Dohna's strength was numerically about the same as the king's, and with his thirty thousand men Frederick had no doubt that he would make but short work of the eighty thousand Russians, of whom some twenty-seven thousand were the Cossack rabble, who were not worth being considered, in a pitched battle.

Deceiving the Russians as to his intentions by opening a heavy cannonade on one of their redoubts, as if intending to ford the river there, he crossed that evening twelve miles lower down and, after some manoeuvring, faced the Russians, who had at once broken up the siege on hearing of his passage.
Fermor sent away his baggage train to a small village called Kleinkalmin, and planted himself on a moor, where his front was covered by quagmires and the Zaborn stream.