Trench warfare
Trench warfare occurred when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire, mines, camouflaged trapping pits, and other obstacles. The area between opposing trench lines (known as "no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
Military strategy
There was still room for triumphs for the strategy of manoeuvre such as Sherman's March to the Sea in 1864, but these depended upon an enemy's unwillingness to entrench. Towards the end of the war, especially in defense of static targets as in the battles of Cold Harbor and Vicksburg, trench networks foreshadowed World War I. Many of the lessons of the American Civil War were forgotten, when in wars like the Austro-Prussian War or the Franco-Prussian War, manoeuvre won the day.