Command Push is a style of controlling military maneuver favoring centralized control.
Command Push is often likened to (or even considered equivalent to) the German term Befehlstaktik: directive orders: the orders say "what to do, and how to do it". The assumption is that the order-giver knows best how to achieve the task. The order-receiver puts their effort into telling their own sub-units how to do the job.
For Command Push to work, the central authority must have an excellent view of the battlefield, and high quality real-time communication with subordinate military units. This gives the central authority a "big picture" with which to create intelligent plans, and the control over subordinate units to orchestrate those plans.
Command Push is contrasted with Recon Pull.
In the context of FreeCiv, the human player operates according to Command Push -- the human knows all, sees all, and controls everything every unit does, and when. This works a lot better in FreeCiv than it does in real life, where practitioners of Befehlstaktik are often branded as "micromanagers" and fail to make the best use of their subordinates' intelligence and initiative.