The Normans and their language

I do not know if this is the correct list in which to post this
question. So please let me know (politely) if it does not belong
here.

Now, the question: I find myself wondering how it is that the
Normans, a Germanic people, came to be speaking Old French, which I
think is something like 95% Latin.

Near as I can guess, it was from daily exposure to the Romans in
the nearby areas.

But was nothing left of their own language? How did they come to
abandon their own roots that way, and assume completely the language
of the people they had conquered?

Can anyone help me with this?

Thank you.

Mordechai Housman