Interior lines is a strategy of warfare that is based on the concept that lines of movement, communication, and supply within an area are shorter than those on the outside. As the area held by a defensive force shrinks, these advantages increase. Using the strategy of interior lines, a surrounded force can more easily supply, communicate, and move its forces around, and can mount a series of surprise attacks on the forces encircling it. This allows a strategy of moving quickly enough and so unpredictably that the surrounding forces would be forced to retreat. Frederick the Great's operational strategy in his prosecution of the Seven Years' War against the French, Russian, and Austrian Empire's separate armies can be considered an example of the advantage of interior lines in warfare. It also gave the Reds a distinct advantage over the Whites in the Russian Civil War. GeneralRobert E. Lee used this technique during the Battle of Antietam during the American Civil War in 1862, and it was used against him by GeneralGeorge Gordon Meade at the Battle of Gettysburg in 1863. Another example of this tactic can be found at the Battle of Rorke's Drift. A vastly outnumbered British force managed to defeat a Zulu army by using the advantages of the small area to defend.