An example of Atticus being brave, helpful and smart is when he shot the mad dog.
The town panics when the mad dog Tim Johnson comes down the street. They know that a rabid dog is very dangerous.
Calpurnia calls Atticus, and he and Heck Tate come toward the dog. Heck knows he can’t make the shot, and he asks Atticus to take it. Atticus has not shot a gun in years, but he agrees.
With movements so swift they seemed simultaneous, Atticus's hand yanked a ball-tipped lever as he brought the gun to his shoulder. (ch 10)
Atticus is clearly worried, but he does not panic. Even though he has not held a gun in a long time, he still has talent.
The rifle cracked. Tim Johnson leaped, flopped over and crumpled on the sidewalk in a brown-and-white heap. He didn't know what hit him. (ch 10)
The kids learn that Atticus can do something after all. He is one of the best shots in the county, and they had no idea.
This incident accomplishes a couple of things for the narrative. First of all, it establishes Atticus as someone to watch. He is a character full of surprises. Symbolically and literally, Atticus protects the town from the rabid dog. This foreshadows the symbolic protection Atticus provides against the rabidity of racism.