How has Henry's regiment failed its task, according to the officer who scolds Colonel MacChesnay? What was its task? ( Chapter 21)

The officer that called them mule drivers rides up, looking wild. He begins yelling at the head of the regiment. According to this man, the troops ruined a successful charge by stopping short of the line about one hundred feet. The men listen to the harsh words for their commander, a colonel, who seems injured by this assessment. He tries to defend the men, saying they went as far as they could. The officer says it was not enough; the charge as an intended diversion was a failure.