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.
Koos de la Rey
Having realised that the traditional Boer tactic of fighting from higher ground exposed them to the superior British artillery, de la Rey insisted that his men and Prinsloo's Free-Staters dig in on the banks of the Modder and Riet Rivers, the first use of trench warfare in the war. The plan was to hold fire until the British had approached close enough for the Boers' advantage in rifle fire to take effect, while making it difficult for the full force of the British artillery to be used. In the early hours the British troops advanced across the plain unopposed, but Prinsloo's men opened fire at long range, the troops took cover and the artillery pounded the Boer trenches. A series of British rushes pushed the Free-Staters back across the ford, and only a counter-attack led by de la Rey enabled the Boers to hold the field until dusk, when they slipped away. De la Rey was wounded and his son Adriaan was killed; he blamed Cronjé for failing to send reinforcements.