I will start from the 'bottom'. An infantry squad consisted of Privates led by Corporals, Sergeants and a Staff Sergeant as the Squad Leader. A number of Squads (actual # changed over the years) comprised a Platoon, managed by a Sergeant First Class and led by a 2nd or 1st Lieutenant. A 'Company' was composed of 3-5 Platoons and was managed by A First Sergeant and led by a Captain. A Battalion was composed of 3-6 Companies. A Lieutenant Colonel was in command of a Battalion. He was assisted by a good sized Battalion Staff group, of which there were normally two Majors - one the 2nd in Command, the Executive Officer, and the other the Operations Officer or S3. A number of other officers, Lts and Cpts were also on BN staff. Losses due to combat and sickness often meant that subordinates had to step in and take charge of units normally reserved for higher ranks. For example, Winters was actually a Captain when he took command of the Battalion, then promoted to Major. In the movie, as in real life, you often saw Sergeants in charge of squads, Staff Sergeants in charge of Plts, Lieutenants in charge of companies. The actual number of men in a WWII infantry company was somewhere in the range of 150-180 (I am at work and do not have my resources) Where each ones was depended on their job. The privates were at the front with their Sergeants and Lieutenants close behind - like a few feet. The Company Cdr would try to be in a position to control his plts so he would normally be behind the company. Where they actually were depended almost completely on what was actually happening so it was not unusual to have officers in direct firefights.