in chapters 5 and 6? why didnt the commanders of Henry's regiment inspire confidence?

No, they do not inspire confidence. The lieutenant suddenly jumps, red-faced, in front of Henry, attempting to keep him there. He swings with his sword. Henry simply continues to run blindly. He falls a few times. As he runs, he sees others running alongside him and hears more fleeing footsteps behind him. He is convinced the regiment is fleeing, chased by the crashing shells.