He looks up to them because they went into battle and weren't afraid, and he is afraid. In The Red Badge of Courage Crane uses much imagery. The reader can imagine this scene and the eyes of the corpse. This same line is also used as a simile. It is comparing a battle to crimson blotches.
Cranes written is also extremely descriptive.
To conclude this is an interesting and realistic story about the Civil War. Anyone who enjoys historical fiction will thoroughly enjoy this book. The Red Badge of Courage was written by Stephen Crane and was first published in 1895.