The German Army’s Schlieffen Plan ultimately failed due to various reasons. In the Battle of the Marne, the Germans were forced to retreat and the Western Front was created, stretching from the English Channel to the Swiss border. Unlike the Eastern Front, there was a stalemate in the Western Front. The Entente and Central Powers attempted to break the stalemate by developing methods of warfare, allying with more countries, opening up new fronts and using more manpower.
Both sides used the instruments of defense, such as trenches, barbed wire, artillery and machine gun, which proved to be more effective than the instruments of attack. This was one of the major factors that contributed to the ongoing stalemate in WWI. The Germans constructed the Hindenburg Line in 1917 in order to improve their defenses. As a result, most attacks were unsuccessful and surprise attacks were also impossible because of the enemy’s obscure observation of troop movements. Because most attacks were unsuccessful, the war became a contest of endurance, a total war, with each side trying to completely destroy the enemy’s economy. Furthermore, both sides developed new methods of warfare in order to break the stalemate. Germany, for example, first used poison gas for the first time in 1916 in Ypres. However, it was ineffective due to its limitations. The attacker could be harmed with a change in the wind, because the poison gas could blow back. Also, the enemies developed gas masks for defense. As a result, the methods were unsuccessful because when a side came up with a scheme, the other side hastily developed a method to counteract and defend itself, which was one of the reasons why the stalemate was long-lasting.