It should also be noted that Sumner was crippled for life by Brooks' attack, and cripples are rarely found in combat.
Incidentally your idol Charles Francis Adams was a close friend and admirer of Sumner's.
Perhaps, but not in this passage from his 1907 Address:
Charles Adams wrote: "One of a community which then looked upon Lee as a renegade from the flag he had sworn to serve, and a traitor to the Nation which had nurtured him, in my subordinate place I directly confronted Lee throughout the larger portion of the War of Secession. During all those years there was not a day in which my heart would not have been gladdened had I heard that his also had been the fate which at Chancellorsville befell his great lieutenant; and yet more glad had it been the fortune of the command in which I served to visit that fate upon him. Forty more years have since gone. Their close finds me here to-day—certainly a much older, and, in my own belief at least, a wiser man. Nay, more! A distinguished representative of Massachusetts, speaking in the Senate of the United States shortly after Lee's death upon the question of a return to Lee's family of the ancestral estate of Arlington, used these words: “Eloquent Senators have already characterized the proposition and the traitor it seeks to commemorate. I am not disposed to speak of General Lee. It is enough to say he stands high in the catalogue of those who have imbrued their hands in their country's blood. I hand him over to the avenging pen of History.” It so chances that not only am I also from the State of Massachusetts, but, for more than a dozen years, I have been the chosen head of its typical historical society,—the society chartered under the name and seal of the Commonwealth considerably more than a century ago,—the parent of all similar societies. By no means would I on that account seem to ascribe to myself any representative character as respects the employment of History's pen, whether avenging or otherwise;[note] nor do I appear here as representative of the Massachusetts Historical Society: but, a whole generation having passed away since Charles Sumner uttered the words I have quoted, I do, on your invitation, chance to stand here to-day, as I have said, both a Massachusetts man and the head of the Massachusetts Historical Society, to pass judgment upon General Lee."
Sumner would have arced out hearing Adams' Lee Address, and history has forgotten the vile Sumner, but remembered with fondness the peerless Robert E. Lee - to the extent that gibbering foamers make post after post after post assailing the Character which Charles Adams so ably defends, brushing aside their childish insults like so many gnats.
Adams had too much class to do the Spivey with Sumner's reputation, but his Lee Address does it for him.