In order to be effective, Army brigades and battalions have to be properly equipped and in good condition. It is the job of the S4 officer on the brigade or battalion staff to ensure that unit soldiers have the supplies they need and that malfunctioning equipment is restored to service in a timely manner. The S4 is often an officer with the rank of captain.
S4s are responsible for logistical sustainment for battalion and brigade level units. They serve on a staff that answers to the executive and commanding officers. When the CO announces the unit mission it is the job of the S4 to make sure that the soldiers are properly supplied and that their equipment is maintained in battle-ready order. To accomplish this goal the S4 runs a section composed of subordinate officers and soldiers trained in logistical functions. These sections are generally responsible for keeping records of who signs out equipment, maintaining equipment and issuing rations to soldiers.
After earning a commission as 2nd lieutenant, officers proceed to their branch training. For future logistics officers, these are the Ordinance Officer Basic Course, the Transportation Officers Basic Course, and the Quartermasters Basic Officers Course. After about four years, these officers will have enough experience in their respective branches to advance to the rank of captain. At this point, they attend the Combined Logistics Captains Career Course (CLC3). CLC3 trains officers in advance logistics techniques and prepares them for advanced responsibilities as a battalion or brigade S4.
The skills needed for this position are similar to other staff officer positions. S4s must have an expert knowledge of how their branch (ordnance, transportation, or quartermaster) fit into the overall scheme of unit logistics. They must also be knowledgeable about the other two logistical branches. S4s should have excellent written and spoken communication skills, since they will have to write many memos an perform many briefings. Finally they should have strong interpersonal skills since they will have to work well with both superior and subordinate officers and subordinate noncommissioned officers and soldiers.
S4s are typically located at the battalion and brigade levels. Brigades are composed of about five battalions. At the company (lower) level, there are no staff positions. At the division (higher) level, the staff positions are designated by the prefix "G" (G1, G2, and so on). There are hundreds of Army brigades and divisions based in the U.S. and around the world. These units all need S4s and have diverse specialties such as infantry, aviation, artillery, military intelligence and training.
After the Army
Army logistics officers who decide to resign their commission have the training and experience to transition into logistic positions with civilian companies. A former logistics officer might work as an operations manager at a transportation company or as a corporate supply chain officer for a manufacturing company. The GI Bill also provides funds that enable former officers to earn advanced degrees after leaving the service.