It is probably no coincidence that the first part of Harper Lee's novel ends with the words of Atticus to his children about Mrs. Dubose to whom he made Jem read as punishment for tearing her camellias. Atticus explains that she withdrew herself from morphine before her death. He says,
I wanted you to see what real courage is. ...It's when you know you're licked before you begin but you begin anyway and you see it through no matter what. You rarely win, but sometimes you do.
In the second part of the novel, Atticus exhibits this undaunted courage as he faces the mob who accost him at the jailhouse. He displays courage as he faces the townspeople who gather in his yard. He uses all his skill to defend the innocent Tom Robinson as he knows that he is probably "licked" before he even begins his case. But, he does the best he can to defend Tom and hopes that perhaps he can win on appeal.
When the children are threatened by the reprobate Bob Ewell, Boo Radley risks his life for Jem and Scout knowing that he could easily by harmed. Yet, he courageously steps out of a house which he has not left in years and rescues the children.