How Similar is Gang Life to Army Life?

  Today in English class we were discussing two Jorge Borges's fictional works based on Herbert Asbury's book The Gangs of New York. The story that will be discussed now is "Monk Eastman: Purveyor of Iniquities".  After being sent to jail and his gang that formally consisted of 1,200 members was dissolved, Monk Eastman commits misdemeanors and is in and out of jail. Monk Eastman eventually decides to "turn over a new leaf" and join the army to fight in WWI. The question in class was whether he actually turned a new leaf. The army from my perspective is a similar structure to the life style that Monk Eastman was used to.Being in a gang involved fighting with competing gangs over boundaries,and stolen goods. Many, if not all wars were started over issues such as boundaries and natural resources, as in goods. Monk Eastman was able to satiate his thirst for blood and gore by joining the army. He was from my perspective not a changed person. He was still doing the activities that he loved, fighting the enemy. The only difference was that: 
1- Killing in combat is legal, while killings resulting from gang fights are illegal.  
2- People who kill in the army are considered heroes, while people who kill other people in gang fights are considered murderers.

   Eastman had the mentality that is consistent with being in the army, staying loyal to his side,and fighting and killing the enemy. Being in a gang also means roughing it, and facing the possibility that you might be injured or killed. Those parts of gang life are also consistent with army life.In many ways army life is very similar to gang life.  
In the end we see that Eastman had never actually reformed himself. He returned to petty crime. On his final day Eastman was shot by Jerry Bohan, a corrupt Prohibitionist  and Eastman's friend. Eastman died from that gun shot .Bohan was sent to jail for three years.The authorities also discovered upon Eastman's murder that he was bootlegging alcohol.He was buried with military honors. So I guess the cliche that, "A tiger cannot change its stripes overnight"  is true.