Just got done reading the Wolfram von Eschenbach translation of Parzifal. It tells the story of the finding of the Holy Grail.
One of the knights, Gawain is laying on a magic bed, then
"This was the signal for an even greater peril for him. Five hundred slingstaves had primed to be thrown by subtle arts, and their cast was aimed at the bed on which he lay. The shield was so tough that he felt their impact but little, hard round pebbles that they were-thought it was holed in several places."