24669
John Keegan argues that the longbows ' main influence on the battle at this point was injuries to horses : armoured only on the head , many horses would have become dangerously out of control when struck in the back or flank from the high-elevation , long-range shots used as the charge started .
 John Keegan
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 John Keegan