Tolkien did clarify his position in the essay
ofermod, which he appended to
The Homecoming of Beorhtnoth in my opinion to add the bare minimum of academic discussion required to justify its presence in a scholarly journal. There he defines quite clearly what he means by 'courage' and 'chivalry', and the important distinction between them.
To my mind, what Tolkien was saying throughout the piece was that courage is shown in doing what must be done, regardless the risks involved. Chivalry is that virtue taken to extremes: giving a disarmed enemy back his weapons so that he can fight on; allowing a surprised enemy to take up their battle formations. Chivalry is needlessly increasing the risks for the sake of personal reputation; courage is accepting the risks that exist and doing one's job regardless.
Joy started
a good thread on Byrhtnoth, Maldon and Tolkien in which we talked about just these issues. I think I concluded that Byrhtnoth, despite its mediaeval pretensions, has entirely twentieth-century concerns.