Politics thus gained a new intensity after the Conquest, and yet they were also less bloody. In the great Anglo-Norman and English battles between 1106 and 1264, as in the more general ravaging warfare, very few nobles were ever killed. The immediate reason, as Orderic stressed, was the protection of armour, but ultimately any knight could be surrounded and disarmed. The key point was that when this moment came he simply surrendered and was taken off for ransom. The institution of ransom was, therefore, absolutely central to the failsafe warfare enjoyed by the nobility in this period. Indeed the whole aim in battle was to capture, not to kill, a noble opponent. There was here a wider context because politics too, not just warfare, was largely bloodless. It is a remarkable fact (and one quite contrary to usual perceptions of the Middle Ages) that between Waltheof’s demise in 1076 and Gaveston’s in 1312 not a single English earl, and indeed hardly a single baron, was executed (or murdered) in England for political reasons.
That is from the excellent and highly substantive book by David Carpenter, The Struggle for Mastery: The Penguin History of Britain, 1066-1284. Wasn’t there also a JLE piece about this kind of warfare?