I've seen this in some movies and video games about world war 2. Basically whenever a ranking officer wanted to signal his troops to suppress an enemy position, he would sort of punch 2-3 times in forward direction. Could someone help me identify what this signal meant.
In World War 2, US troops almost never used standardized hand signals. That was an invention of the Vietnam War, and even then was primarily used by Rangers and special forces, not everyday soldiers.
Various modern movies, notably "Band of Brothers" and "Saving Private Ryan", anacronistically show actors using hand signals. If you watch contemporary war movies, like "Sands of Iwo Jima" or "Objective: Burma", you will see no hand signals, except maybe a hand wave beckoning ("come forward").
The British used hand signals occasionally and their double time signal, fist up and down, was widely copied by American on the western front.