With the withdrawal of Russia from World War I, the Germans were able to reinforce their western front with troops from the eastern front. This allowed them to take units out of the line and train them in new methods and tactics as stormtroopers. The new methods (involved men rushing forwards in small groups using whatever cover was available and laying down covering fire for other groups in the same unit as they moved forwards. The new tactics, (which were to intended to achieve tactical surprise), were to attack the weakest parts of an enemy's line and bypass his strongpoints, and to abandon the futile attempt to have a grand and detailed plan of operations and control it from afar, instead junior leaders on the spot could exercise initiative. These tactics proved very successfull in the attack the German 1918 Spring Offensive against British and Commonwealth forces.

During the last 100 days of World War I the British forces broke through the German trench system and harried the Germans back towards Germany using infantry supported by tanks and close air support. Between the two world wars theses techniques were used by J.F.C. Fuller and Liddell Hart to develop theories about a new type of warfare. The ideas were picked up by the Germans who developed them further and put them into practice with the use of Blitzkrieg. Blitzkrieg relied on the concentration of armour launched at a narrow front to make the break through followed by a high speed encirclement of the enemy's front line. The armour was supported by close air support with airmen inserted into army units to direct tactical air strikes.

The stunning victories by the Germans early in the World War II war using blitzkrieg showed that the investment in fixed fortifications like the Maginot Line were not cost effective. The amphibious landing by the Western Allies in 1944 smashed through the Atlantic Wall with relative ease. The fight inland through the bocage proved far more of an obstacle than the fixed fortifications of the Atlantic Wall.

Combined arms warfare, where infantry, light artillery, and (if possible) tanks and aircraft operated in close cooperation made trench warfare obsolete. The basis of modern land warfare remains based in semi-autonomous small teams such as the fire team and still places a large emphasis on rapid communication and allowing smaller units to exercise initiative.

This is not to say that entrenchment is redundant. It is still a vary valuable method for reinforcing natural obstacle for creating a line of defence. At the start of the last large major assault of World War II, the Russians attacked over the river Oder against German troops dug in on the Seelow Heights which are about 50 [Km]] east of Berlin. Entrenchment allowed the Germans, who were massively outnumbered, to survive a barrage from the largest concentration of artillery in history and to inflict tens of thousands of casualties on the Soviets, thanks to the marshy land which lay between the river and the heights, before (after a few days,) being driven west by weight of numbers.