To protect tom from the mob!
Jem initially follows Atticus to the jailhouse and tries to protect him from the angry mob. He stands up to the men and shows courage, but ultimately it is Scout's innocent interference that diffuses the situation.
Heck Tate, the sheriff of Maycomb, asked Atticus Finch to shoot Tim Johnson, the rabid dog, because he believed Atticus was the best shot in town. Atticus reluctantly agrees and demonstrates his excellent marksmanship by taking down the rabid dog with a single shot.
He wanted to go home the short way
The compromise that Atticus makes with Scout about school is that if Scout continues to go to school then he will continue to read to her at night. This is from the book To Kill A Mockingbird.
In the middle of the night I go walking in my sleep.
Atticus Cain goes by AC.
I'm assuming this is about To Kill A Mockingbird. I just finished this in class. In those days, it was common for mobs to go and lynch (or kill) a black man before his trial. It was easier in their eyes, and the local government just turned a blind eye. Atticus went there to protect Tom Robinson from the mob that inevitably came.
Atticus wakes up his children in the middle of the night to go to Mrs. Maudie's house because her house is on fire. The incident serves as a dramatic event that brings the community together and marks the end of innocence for Scout and Jem. The killing of the mockingbird symbolizes the loss of innocence and the harsh realities of life.
To see if Atticus is responsible
The men go talk to Atticus at his house because they are members of a mob looking to harm Tom Robinson, and they want to confront Atticus about defending him in court. They are seeking to intimidate and threaten Atticus to stop him from continuing with the trial.
Atticus leaves the house late at night to go to the county jail to protect Tom Robinson from the potential threat of a lynch mob. What's unusual about his departure is that he doesn't tell his children where he's going or why, which goes against his usual openness and honesty with them.
He tells her that if she promises not to tell Miss Caroline about them reading at home, but continues to put up with her and her antics and continue to go to school, then they'll keep reading every night.