Arthur hector whack

When Hector, who was near Lancelot, saw that blow,
he was angered, for he feared that Lancelot was injured; he
charged the king and struck him so hard on the helmet
that he was stunned and did not know whether it was night
or day. Hector, who knew it was the king, dealt him
another blow, so that Arthur was unable to hold himself in
the saddle but was flung to the ground beside Lancelot.
Then Hector said to Lancelot, “Sir, cut off his head, and
our war will be ended.”
“Hector!” said Lancelot. “What are you saying? Don’t
say that again, for it would be wasted breath.”
With these words Lancelot saved King Arthur from
death, for Hector would have killed him.

The Vulgate Cycle