This chapter's quote is from Shakespeare's Two Gentlemen of Verona, which Scott also uses at the beginning of Chapter 11. These lines are from Act V, Scene 4, when Proteus threatens the female lead, Silvia, with rape.
At around noon the following day, De Bracy appears in Rowena's rooms.
He has taken the time to get all dressed up to impress her.
De Bracy tries to woo Rowena, but she isn't having it. He has taken her and her father captive, after all.
De Bracy loses his temper. He tells Rowena that she will either leave Torquilstone as his wife or not at all.
De Bracy has no idea how she can refuse him – to his mind he's a Norman and rich, while she's a just a lowly Saxon.
De Bracy assures her that Wilfred of Ivanhoe will always be penniless because his friend King Richard will never come back to England.
If Rowena will marry De Bracy, he'll make sure that Front-de-Boeuf doesn't kill Ivanhoe.
After all, Ivanhoe is Front-de-Boeuf's competitor for the castle of Torquilstone, so Front-de-Boeuf has good reason to assassinate him.
If Rowena does what De Bracy tells her, then De Bracy will rescue both Ivanhoe and Cedric. How can she refuse?
Rowena starts to cry.
De Bracy feels embarrassed. He can't go back on his plan now, but he can't talk to her while she's crying.
As De Bracy tries to calm Rowena down, he hears the three horn blasts at the gate.
De Bracy is relieved to have an excuse to leave the room.
The narrator jumps in to say that it's weird that the same people who went on to help protect English liberty (in other words, the Norman nobility) started out so oppressive.
He lists many other examples of the cruelties of the Normans.
Basically, the 11th and 12th centuries were not a great time in English history.