Trench warfare
Trench warfare prevailed on the Western Front from late 1914 until the Germans launched their Spring Offensive on 21 March 1918. After the buildup of forces in 1915, the Western Front became a stalemated struggle between equals, to be decided by attrition. Frontal assaults, and their associated casualties, became inevitable because the continuous trench lines had no open flanks. Casualties of the defenders matched those of the attackers, as vast reserves were expended in costly counter-attacks or exposed to the attacker's massed artillery. There were periods in which rigid trench warfare broke down, such as during the Battle of the Somme, but the lines never moved very far. The war would be won by the side that was able to commit the last reserves to the Western Front.
Trench map
These first trench maps, used until the Summer of 1915, also suffered from a lack of standardization. In the absence of a single, theatre-wide format for trench maps, some rather idiosyncratic patterns came into being in these early days of trench warfare. For example, on the British 1st Army Front, troops used the notorious maps that the intelligence officer Col. Charteris favored, which actually printed the North on the bottom and the East on the left-hand side of the map! In addition, the inverted Charteris maps lacked an over-printed grid with hash-marks, so that individual targets required individual target reference numbers. The British Army had to fight two of the largest early battles of the war, those of Aubers Ridge and Festubert, using these wholly unsatisfactory maps.