My View of SB:First World War

[jomni]

Actually platoon sized units during the start of the war. (Old style mass maneuver tactics)
By late war, the unit composition changes to smaller squads and their fire power increases with portable automatic weapons. (Infiltration tactics).

Squad battles is a good lesson in the evolution of small unit tactics where more and more autonomy is given to squads as firepower increases.

In the modern times, Squads are even split into Fire Teams (Falkland, Modern War).