Sentence:  But on that day when Lancelot fled the lists, / His party, knights of utmost North and West, / Lords of waste marches, kings of desolate isles, / Came round their great Pendragon, saying to him / 'Lo, Sire, our knight thro' whom we won the day / Hath gone <WSD>sore</WSD> wounded, and hath left his prize / Untaken, crying that his prize is death.' 
Meaning of the word marked with <WSD> tags:  Very, excessively, extremely (of something bad).