It is true, in front of McClernand there was a small force of the enemy and posted in a good position behind a ravine obstructing his advance; but if he had moved to the right by the road my staff officers had followed the enemy must either have fallen back or been cut off.

Instead of this he sent orders to Hovey, who belonged to his corps, to join on to his right flank.

Hovey was bearing the brunt of the battle at the time.

To obey the order he would have had to pull out from the front of the enemy and march back as far as McClernand had to advance to get into battle and substantially over the same ground.
Of course I did not permit Hovey to obey the order of his intermediate superior.
We had in this battle about 15,000 men absolutely engaged.

This excludes those that did not get up, all of McClernand's command except Hovey.