Edward Ashburnham is, ironically, neither very good nor much of a soldier. Though Dowell assumes he is strong, upright, and "exactly the sort of chap that you could have trusted your wife with," his assessment proves incorrect. Edward's goodness extends only so far as it can bring him personal honor. He is a generous magistrate, allowing tenants to remain on his land, thus endearing him to his people. He is also heroic; he willingly jumps into the sea to save a man who has fallen overboard. But the novel suggests that there is something selfish in these heroic acts, which allow passion to overcome practicality and concern for the well-being of his family.
Edward cheats on his wife relentlessly, and though Dowell dismisses his infidelity as the consequence of his passionate and sentimental nature, Edward nevertheless deeply hurts and offends Leonora. Such flippancy in hurting one so close to him must be considered an important facet of his character. But Captain Ashburnham is not completely immoral; he refuses to act upon his feelings for Nancy. Eventually, this thwarted passion destroys him.
Edward is old-fashioned; he strongly values his land and his family's name. He is not vulgar, and he is horrified at the thought that his wife might know the truth about his affairs. Edward's character is ultimately ironic, for he is the very opposite of what he appears to be. His suicide is not an act of heroism, as Dowell claims it is. Killing oneself with a penknife is not a brave way to die. Instead, his death is the ultimate capitulation to his wife's power.