On the next day Alexander pledged himself to withdraw his army at once; and Francis proceeded to treat for peace with Napoleon.

This was an infraction of the treaties of the Third Coalition, which prescribed that no separate peace should be made.
Under the circumstances, the conduct of the Hapsburgs was pardonable: but the seeming break-up of the coalition furnished the Court of Berlin with a good reason for declining to bear the burden alone.

It was not Austerlitz that daunted Frederick William; for, after hearing of that disaster, he wrote that he would be true to his pledge given on November 3rd.

But then, on the decisive day (December 15th), came the news of the defection of Austria, the withdrawal of Alexander's army, and the closing of the Hapsburg lands to a Prussian force.

These facts absolved Frederick William from his obligations to those Powers, and allowed him with perfect good faith to keep his sword in the scabbard.