They declared in Robert's favour, and retired to their castles (those castles were very troublesome to kings) in a sullen humour.

The Red King, seeing the Normans thus falling from him, revenged himself upon them by appealing to the English; to whom he made a variety of promises, which he never meant to perform--in particular, promises to soften the cruelty of the Forest Laws; and who, in return, so aided him with their valour, that ODO was besieged in the Castle of Rochester, and forced to abandon it, and to depart from England for ever: whereupon the other rebellious Norman nobles were soon reduced and scattered.
Then, the Red King went over to Normandy, where the people suffered greatly under the loose rule of Duke Robert.

The King's object was to seize upon the Duke's dominions.

This, the Duke, of course, prepared to resist; and miserable war between the two brothers seemed inevitable, when the powerful nobles on both sides, who had seen so much of war, interfered to prevent it.

A treaty was made.