The E4 army is section of the army that comprises about one-fifth of the total number of members in the army. In this group are specialists and corporals. They total over 100,000 strong and hold a large sway in how the Army functions due to the fact that so many responsibilities fall on their shoulders.
The rank of specialist is an unofficial group leader. Usually leading and helping a small group of other soldiers of lower rank they make sure all work is done and that they are all proficient in the task that they are doing. This means that a lot of the day-to-day work falls on the specialist’s shoulders orders from above come down to them to make sure the work is actually getting done. All of this occurs while the specialist performs whatever other job they are tasked with as well.
The other position in the Army that shares the rank of E4 is corporal. While technically above specialist in rank they are on the same pay grade. The corporal's job to make sure that the service members meet military standards for job performance, physical fitness, appearance. They play this role for soldiers both on and off duty. Another job Corporals serve is as a resource for service members under their supervision and as liaisons with higher-ranking military personnel. These tasks may seem similar to the specialist, but they are a little more in-depth.
This means that all ranks under E4 are essentially directly taken care of by the E4’s. This is one of the reasons why E4’s position is as large in numbers as it is. Aside from the day-to-day job description that E4’s hold there is a deeper meaning to the E4 army. The other side of being an E4 is referred to as the E4 mafia. The E4 mafia is a loosely used term to reference the comradery that many E4’s feels towards each other and their tendency to collaborate and work with each other to spread rumors, collect information and mess with both lower and higher ranks alike.
Due to the size of the rank, E4’s usually winds up collectively knowing more about and controlling more of the day-to-day operations of the Army. This power has often annoyed officers and sergeants who despite their higher rank have trouble controlling all of the E4’s under their watch.
Because E4’s are on top of their respective totem pole of limited command before reaching the rank of sergeant, many opt-out of being promoted and choose to stay in their comfortable position instead. In many ways, there are fewer benefits to getting a promotion than there are to going up to an E5.
In the end, E4’s are the critical backbone of the Army and they are well aware of that fact and use that to their advantage. Whether you are talking about the literal job that they perform or the not so secret connection they all share with each other in the “E4 Mafia” they really do act like their own separate section of the Army and without nothing much would ever get done.