A creeping barrage
is an artillery tactic
first used during the trench warfare
of World War I
. A barrage
is the use of a number of guns firing in sequence so as to create an area that is undergoing continuous bombardment
. Initially, during that war, artillery was used primarily as a preparatory measure. Prior to an infantry assault on trenches or other fortified positions, artillery would be fired for some period of time at the target area in an attempt to destroy, degrade or disrupt both the fortifications and the defending forces. Once the target had been 'prepared' for the maximum available time or maximum available ammunition
expenditure, ground forces would attack.
The problem, as both sides figured out relatively quickly, was that defending troops could in fact learn to survive artillery bombardment. Deep slit trenches and bunkers made it much less likely that troops in the target area would be hit, even with the large numbers of shells used, as the attacking artillery was not able to directly target them. Even after a long barrage, damage inflicted could be relatively quickly made good enough to deny foot infantry a viable attack path, and under anything but the most maximum effort barrage, such repairs and reworking could even take place while still under attack if there were enough shielded or countersunk positions to work from.
As a result, the creeping barrage (also called the walking barrage) was invented. It specifically recognizes that the main short-term effect of artillery attack is not destruction, but disruption; the physical effect on men in the target zone as well as the organizational disruption caused by communications systems being damaged. In order to maximize this effect at the time of the infantry attack, the creeping barrage was used. In a creeping barrage, the firing guns continuously and slowly increase their elevation (and sometimes also change their deflection) so that the barrage area is not static, but in fact advances towards the enemy at something approximating a walking pace. The attacking infantry follows just behind the barrage area. When the artillery reaches the target area, it may sometimes intensify for a time, but then either traverses past it or lifts to attack targets in the enemy rear area to prevent reinforcement of the target. The infantry then attacks when the barrage has cleared their target.
This was much more effective than static barrage prep. It was the creeping barrage that began the transition of battlefield artillery from a static, open-sight force to a truly indirect weapon, governed by mathematics and planning rather than by eye.
Although the creeping barrage was in essence a purely two-dimensional effect, both sides experimented with different fusing in attempts to produce airbursts rather than ground bursts for maximum lethal radius. In an extreme thought experiment on this, Philip Francis Nowlan wrote of special creeping barrages in his book Armageddon 2419 AD - the seminal "Buck Rogers in the 25th Century" novel. In it, he posited an artillery of extreme dispersal, but equipped with gunnery computers and rocket shells which could, from widely scattered positions, nearly instantly produce coordinated creeping barrages that not only could traverse the land but could be 'walked' up into the air to cope with flying or high-jumping threats. Fifty years later, modern armies with MLRS and its equivalents can do, in fact, precisely that.