Picture that great scene in Shakespeare's Richard III. King Richard, alone on the crest of a hill,

Question:

Picture that great scene in Shakespeare's Richard III. King Richard, alone on the crest of a hill, his horse lost, his sword drawn, facing the oncoming enemy, shouts: "A horse, a horse, my kingdom for a horse!" Translate and explain his desperate cry in terms of marginal utility analysis. What do you suppose the marginal utility of a second horse would be to Richard?