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.
Trench map
Partly in response to the evident deficiencies of such maps, the British Army put into use, starting in July 1915, the "Regular Series" trench map. These Regular Series maps, printed in Britain, did much to improve the situation (all 1:10,000 scale maps in this series, printed by the Geographical Section of the General Staff, bear the GSGS number 3062; 1:20,000 scale maps of this series bear the GSGS number 2742; maps of this series were almost invariably backed with linen, greatly improving their durability). Even after the Regular Series came into use in the Summer of 1915, however, local editions of maps, of different formats and printed at the front, remained in use, and did so throughout the war.