The First World War was a war of mass production. The U.S. Civil War introduced the machine gun, but during the entire war there may have been fewer than 100 machine guns of different designs in use, including perhaps 23 Gatling guns. In World War I there may have been upward of one million machine guns manufactured. Artillery, though, was king of the battlefield: Most casualties were caused by shell fire. Over 700 million artillery shells were fired during the war. The countermove from the science of defense was to dig deeper into the earth. One calculation claims it took 329 shells to wound an opponent sheltering in a trench, four times that to kill him. [Enduring the Great War: Combat, Morale and Collapse in the German and British armies, 1914–1918, by Alexander Watson, Cambridge University Press, 2008]
Yet even with armaments occupying a larger and larger share of national production, the deadlock persisted. C. S. Forester in his 1936 novel The General unkindly and rather inaccurately compared the protagonists with savages trying to pull a screw out of a piece of wood by using larger and larger levers. The problem with the analogy is that both sides in the war were desperately trying to find a way of turning the screw.
Science and technology provided one possible way out of the deadlock. The Germans first used toxic chlorine gas on a large scale in April 1915, initially with great effect. We noted J.B.S. Haldane’s assessment of the gases as “brutally barbarous” [June 12, 1915] but gas masks were quickly developed, manufactured and shipped. As the war progressed, both sides developed and deployed ever more lethal forms of poison gas, with the science of respirators almost keeping up with the chemical weapons. Perhaps 1 percent of military deaths from the war were due to gas—Michael Duffy on FirstWorldWar.com says about 90,000 died. But many more were wounded, taxing medical resources and leaving a strong impression on soldiers on the front line. Gas had an outsize psychological effect on those who witnessed it. The most horrific poem to come out of the war, written by Wilfred Owen, is about a gas casualty: “If you could hear, at every jolt, the blood/ Come gargling from the froth-corrupted lungs.” For the generals charged with the duty to win the war, gas was useful because it had a material effect on men (and horses). Even though the use of gas against troops supplied with gas masks caused comparatively few casualties, soldiers could not operate as quickly and effectively while wearing the clumsy protection: The task of drawing a breath past the filters required effort, and any great muscular exertion—for instance carrying boxes of ammunition through clinging mud—became a torturously slow affair. The first gas was deployed from canisters; the next technological step saw it loaded into shells and fired by artillery far across the front line trenches. Propaganda frequently condemned the use of poison gas by the enemy, but on the Western Front all sides used it often.
The airplane was an invention barely a decade old, and it quickly proved highly valuable in the reconnaissance role. As the war progressed, we tracked the development of faster and more reliable airplanes wielding cameras, shotguns and machine guns. The armed fighter plane became a fixture over the battlefield, where air superiority translated into the ability to control the flow of information to military commanders. Huge bombers were developed later in the war. Certainly their potential was recognized: “The tremendous possibilities of destructive warfare and the very great material and moral damage bombing machines may accomplish.” But it is possible that the greater part of the effect was as a morale booster for the attacking force: “The start of an American bombing squadron from the French front on a raid into German territory was a spectacle to stir the enthusiasm of any American and inspire him with an appreciation of Uncle Sam's rapidly growing strength in the air” [December 7, 1918]. A relatively small bomb load and inaccurate targeting meant that airplanes were not significant for decades. Later in the war the airplane and spotting balloon coordinating with artillery became a truly formidable weapon when the eyes of the pilot (or lens of the camera) gave accuracy to the weight of shell fire.
Barbed wire—dense thickets of it, not the polite strands used by farmers—was used on a massive scale where terrain and territory favored static warfare. But an attacker could go under the barbed wire if he had patience and time: Mining under the enemy’s defenses was carried out on a wide scale by all sides [June 9, 1917, cover & p. 579], occasionally with astounding success. The tunnels under Messines Ridge took 18 months to build; when 19 underground mines were detonated under the German lines, 10,000 soldiers lost their lives. By the end of the war, tanks (light and heavy) were quite capable of going through or over wire entanglements, finally ending the defensive advantage of barbed wire.