Sentence:  Then Sir Galahad began to break spears marvelously, that all men had wonder of him; for he there surmounted all other knights, for within a while he had <WSD>defouled</WSD> many good knights of the Table Round save twain, that was Sir Launcelot and Sir Percivale. 
Meaning of the word marked with <WSD> tags:  To physically crush or break.