Vanguard (military formation)

The vanguard (also called the advance guard) is the leading part of an advancing military formation. It has a number of functions, including seeking out the enemy and securing ground in advance of the main force.

The vanguard derives from the traditional division of a medieval army into three battles or wards; the Van, the Main (or Middle), and Rear. The term Vanguard originates with the medieval French avant-garde, i.e. "the advance guard". The vanguard would lead the line of march and would deploy first on the field of battle, either in front of the other wards or to the right if they stood in line.

The makeup of the vanguard of a fifteenth-century Burgundian army is a typical example. This consisted of

In an English force of the period, the foreriders of the vanguard would be accompanied by the harbingers, whose job was to locate lodgings for the army for the following night.

During the Soviet-German War (1941-1945), beginning in July, 1943, the Red Army began forming, as part of its offensive doctrine, ad hoc vanguard formations called forward detachments [peredovye otriady], from army, corps and divisional units. Forward detachments brought together the mobile (motorized or mechanized) elements of the parent formation to play an exploitation role once a breakthrough of the German lines occurred. A rifle division, for example, might mount one or two battalions of infantry on trucks, with motorized antitank guns and motorized artillery in support.

...
Wikipedia