How does henry become " pompous and veteranlike "? at first, he felt justified in running from battle then ashamed. how does he reinterpret his past actions and rebellious thoughts now

Henry understands that most men had run away from battle. He realizes that running away was not an act of cowardice but rather an act of self-preservation. Running away from almost certain death was instinctual: like wanting air if one was drowning. Henry uses this experience as part of being a soldier rather than not being a soldier.