Skirmish
The modern US military has light rapid-deployment Stryker brigade combat teams working with heavy-mechanized and armored units, with tracked M2 Bradley infantry fighting vehicles and M1 Abrams tanks forming the primary combat force.
Apartheid South Africa's military doctrine stressed the use of highly-mobile, light-mechanized forces that could cover ground swiftly while they kept heavier enemy armoured and infantry formations off balance and did not engage until the conditions were favourable. The lightly armed South African units used tactics such as rapid movement, flank harassment and confusing the enemy with continuous maneuvering to compensate for their inferiority in firepower when they were faced with Angolan and Cuban forces during the South African Border War. The innovative use of South African reconnaissance units to throw Angolan tank formations into disarray before it lured them into ambushes, effectively deploying the units as skirmishers, was another consistent feature of that conflict.

See also: Battle
Demoralization (warfare)
Francs-tireurs
Grenz infantry
List of military tactics
Picket (military)
Raider
Rifleman
Scouting

References: 

Sources: Randolph, Lewis Hamersly, Biographical Sketches of Distinguished Officers of the Army and Navy, Henry E. Huntington Library: New York, 1905.

Further reading: "Light Infantry", special issue of Ancient Warfare, 2/1 (2008)

External links: Skirmish tactics during the Napoleonic wars: skirmishing, skirmishers