Skirmish Warfare
The term Skirmish Warfare refers to the tactic of continually retreating your forces out of range of enemy forces, while using superior missile troops to destroy opposing ranged threats. It is often used in multiplayer as a counter to an enemy's superior melee army.
Details
History in Total War
The need for skirmishing troops originally came about in Shogun: Total War when facing an army with superior melee troops. Actually, skirmish tactics had been used in other strategy games before, but the scale and morale system of Total War allowed skirmish warfare to be employed at a larger scale than ever before, with devastating effects.
Attempts to catch a purely skirmish army usually failed, due to the proficiency of such armies in mobility; generally, unless a mistake was made by the opposing army, the only way to counter skirmish armies was to skirmish yourself. The resulting battle is known as a missile war.