1) Facing his fear as battle approaches.... questioning the other soldiers to get a gauge on their fear (most aren't happy with his questions)
2) The first time he sees a dead man, and the look in the dead man's eyes
3) Henry is traumatized by his own actions when he runs away from battle.
4) Jim Conklin's death
5) receiving his own "red badge of courage"
6) Henry was proud of his actions only to be called a "mule driver." The conversation he heard also alluded to the fact the mule drivers were expendable.
7) Henry is effected when he spends time with the captured soldiers and realizes they're just like him.