The environment that Bierce chooses helps to express his theme. The stories environment takes place on a battlefield after a recent battle. Many people are lying around hurt, suffering, and on their way to meet their maker. The reason Bierce chooses this type of environment is he is ultimately trying to make a case for allowing assisted suicide and show that the Captain's actions were acceptable. Bierce chose the perfect environment to assist in supporting his theme.
The character heredity was designed to have a specific outcome. The three main characters were the Sergeant, Captain, and Major. The Major and the Sergeant were brothers serving in the war together. The Sergeant also had a relationship with the Captain. Even though they were not related by blood, many would consider them close enough to be brothers. The twist though is that between the Major and the Captain existed one of the fiercest rivals. The two absolutely hated each other and would love nothing more than to see the other one dead. The Captain's motivation to kill the Sergeant was strictly out of love for his friend. He knew he was going to die soon and couldn't stand to watch his friend suffer on the ground wounded. The Major's motivation to kill the Captain though was due to his hatred for him. When he saw the Captain put his sword through his brother's chest, he ordered him to face a firing squad. If these characters were not related in this specific way, the outcome