The clearest description we receive of March in this book is actually in Chapter 14, when Marmee travels to visit him in hospital when he is greviously ill, and sees the transformation that his various trials have enacted upon him. So great is this transformation that Marmee herself even says that if she had not been given explicit instructions from the nurse about where to find her husband, she would not have been able to recognise him. This is partly because of the massive loss of body weight he has experienced, and partly because of the wounds he has suffered. Note how Marmee describes his hair:
When he set out, his hair had been gold, lightened here and there by the silver streaks of his maturity. Now, what hair he had was entirely grey, and scalp showed where hanks had fallen out entirely.
This quote is therefore useful when considering the obvious contrast between March before and after his illness. In Chapter 2, when March recalls his eighteen-year-old self, he described himself as "lean and strong" with sun-bleached hair. The difference in the description indicates just how much his experiences of war have actually changed him. He is now a man diminished, just as his own concept of morality and ethics, that were so strong and sure, have diminished as well.