Elastic Defense, also known as Defense in Depth was a tactical doctrine that was used in various forms by different nations during World War II, notably Germany and Japan. The Elastic Defense’s basic principles consist of minimizing casualties to one’s own side while maximizing casualties to the other side’s troops. To do this, an elastic defense would give up land to the enemy in exchange for retaining a defensive line. Where more strongly fortified defensive lines could be broken if given enough pressure, an elastic defense would have multiple lines of less fortified defenses each protecting the other, weakening the enemy over time rather than plainly holding back any attempt at advance.
German Elastic Defense doctrine called for the creation of three defensive zones, the ‘Outpost’ zone, the ‘Battle’ zone, and the ‘Rearward’ zone. The Outpost zone would be occupied by only the minimum amount of troops required to maintain constant observation and combat enemy reconnaissance. The Battle zone, typically having anywhere from 1,500 to 3,000 meters in depth, was where the enemy was to be worn down over time. Meanwhile, the Rearward zone would hold the majority of heavy artillery or anti-tank weapons that would aid to defeat the enemy in the Battle zone. When the enemy was finally worn down enough, German troops would use the reserves that had been saved from a concentrated defensive line and launch prompt counterattacks so that the defensive line would "bounce" back to its original point.
Following the First World War, the German Elastic Defense remained largely unchanged, yet was felt by many German commanders to be unfit for the new war. Some concessions made to allow for a more mobile defense were the more sparing use of trenches, instead replaced for fox holes and strong points, though tougher defenses were always sought after. Furthermore, the anti-tank gun was given far more precedence in the design of the position. Another important feature of the German Elastic Defense was the use of a false first trenchline, typically used on the Eastern Front. What this did was absorb the majority of Soviet artillery fire while German troops quickly moved back to rear positions, as soon as the barrage ended, they moved into this first line so as to counter enemy advances. Examples of the German Elastic Defense can be seen in many instances during the war, notably, the fighting in Normandy in the Bocage country.
The Japanese Elastic Defense can largely be seen in the remnants of the many fortified bunkers still existing on Pacific islands today. Particularly towards the end of the war, many Japanese military commanders realized that any attempt to simply stop American advances on islands at the beachhead would be foolish and a waste of resources as it would be impossible. What instead should be done is create many different defensive positions, each protecting the other and attempt to "bleed" the enemy until they cannot continue to expend troops and material. Notably, these defensive positions were often well hidden and maintained sound fire discipline so as only to use up ammunition when many enemy casualties could be ensured. This made it exceedingly difficult for Allied troops to dislodge Japanese positions with artillery or air strikes as they largely only became visible while firing.
The principles for the Elastic Defense first originated during the First World War, though examples of similar doctrines can be found in earlier points in history. Initially adopted by the Germans in 1917, the Elastic Defense was also quickly adopted by various other nations in one form or another. It was favored for its ability to allow armies to counterattack swiftly and encircle weakened units before they could retreat. Examples of other nations adopting the defense include the Soviet defense of Kursk in which the usage of heavy artillery and many defensive lines allowed for a counterattack to push the Germans far past their original lines. Britain also used similar defenses in preparation for landings by Germany. However, today, it has largely been abandoned as a military tactic, though has gone on in the form of smaller or more basic versions.
- Wray, Timothy A. Standing Fast: German Defensive Doctrine on the Russian Front During World War II. University Press of the Pacific (2004), Page 3
- Sledge, E.B. With the Old Breed at Peleliu and Okinawa. Presidio Press (2007), Page 138