In
Sun Tzu's
The Art of War, military leaders are advised to take high ground and let the enemy try to attack from a lower position. Fighting from an elevated position is said to be easier for a number of tactical reasons. Holding the high ground offers an elevated vantage point with a wide
field of view, enabling surveillance of the surrounding landscape, in contrast to valleys which offer a limited field of view. General
Ji Ling of the late
Eastern Han dynasty used this principle to his advantage by sending lookouts to positions of higher-ground to scout for and provide early warning about enemy troops. Additionally, soldiers fighting uphill are assumed to tire more quickly and will move more slowly, when compared to soldiers fighting downhill, who do not have to struggle against the forces of gravity alongside natural obstacles in the terrain. Furthermore, soldiers who are elevated above their enemies can get greater range out of low-speed projectiles (such as rocks, javelins/spears, arrows, grenades, etc.), whereas low-speed projectiles have a shorter range when thrown uphill. Very steep and/or rocky terrain, like mountain sides, can be an obstacle to
tanks and
armored personnel carriers, or in the past to
cavalry and
war elephants. For example, in the
Soviet–Afghan War,
mujahideen guerrillas based themselves in the mountains of
Afghanistan, thereby protecting themselves from the
Soviet motorized divisions. This forced the Soviets to rely heavily on
helicopters to conduct the war, but the
United States gave the mujahideen
FIM-92 Stinger anti-aircraft missiles, which, arguably, combined with the defense of the mountains, was able to win the war for the mujahideen. High ground was also employed in the 1423
Battle of Horic in
Bohemia, where
Taborite soldiers took to high ground, forcing the
Utraquist cavalry to dismount to attack them, and also rendering their cannons ineffective. Taborite soldiers were eventually able to make a downhill charge and wipe out the remaining Utraquists. Here again, high ground played a crucial role in the outcome of the battle. However, getting the high ground is not always advantageous. In the
Battle of Jieting of the
Three Kingdoms period of
China,
Shu Han forces occupied a hilltop, which
Cao Wei forces soon surrounded and isolated the Shu forces from water supplies and reinforcements. The Shu forces suffered a humiliating defeat, and the Shu
northern expedition had to be aborted. == As an idiom ==