The 19th century vision of a peaceful future fed by ever-increasing ever-comforting technology was largely shattered by the war, and after the technological escalation during World War II it was apparent that gains in comfort due to technology applied to civilian uses, were often or always outweighed by pains of war when they were applied to conflict. By 1950 no trace of this early optimism remained.
The new metallurgical and chemical industries, and many innovations in mechanical inventions, had created new firepower that made defense almost invincible and attack almost impossible.
The fairly recent innovations of bolt-action infantry rifles, rifled artillery, zigzag trenches and machine guns, which had not existed in any numbers in the 19th century, had the effect of making it difficult or nearly impossible to cross defended ground. The hand grenade originated when desperate and cornered troops made small bombs out of gunpowder, nails, pottery shards, and
hurled them into trenches too dangerous to enter and clear by small arms fire.
Although it had been banned in the Hague Conventions of 1899 and 1907, Germany turned to its best-in-the-world chemical industry, making more than 80% of the world's dye and chemical production as of the war's outbreak, for first mustard gas and then chlorine gas in March 1915. Allied fire punctured metal canisters and released it on German troops at the Battle of Ypres in Belgium, but it was moved up to the North of the salient, where North African French colonial troops encountered a cloud several kilometres wide that suffocated them to death. A large gap opened up in the salient, which could have meant capture of 50,000 troops, if not for a quick shift of Canadians into the line, who threw them back only with very desperate measures. On the 24th the Canadians suffered the second gas attack of the war - using wet handkerchiefs and urine on rags to substitute for the gas masks they did not yet have, and losing 6000 men in three days. Gas however is merely a form of killing and maiming, and a good example of weapons being made of peace. In 1918, Fritz Haber was awarded the Nobel Prize in Chemistry for Haber Process (which was first used on an industrial scale to produce munitions, but also useful for fertilizer).
Phosgene was introduced also in 1915, with the advantage that it does not have the obvious impact - it inhibits transfer of water in the lungs and suffocates without warning. It was a form of harassing fire used on artillery, who often did not wear gas masks.
The British in September 1915 attempted also to use gas but it backfired. It tended to be used in response to prior gas attacks in any given battle.
Radio sets were too heavy to carry into battle, and phone lines laid were quickly broken. Runners, flashing lights, and mirrors were used, but dogs were used only rarely, as troops adopted them as pets and even volunteered to go as runners in the dog's place. Aircraft (called contact patrols) that would fly over enemy lines and drop a message in code back on headquarters.
Sapping, mining under enemy positions, was highly advanced, and specialized tunnelling companies were formed, usually from peacetime specialists, or clay-kickers, who had dug small tunnels, often on their backs using their feet to kick out the clay, under cities (for gas mains and sewers and electrical lines). They were able to plant listening devices close to the enemy's trenches and listen to their activities.
The new long-range artillery developed just before the war now had to fire at positions it could not see. Typical tactics were to pound the front lines and them stop to let infantry move in - merely hoping that the enemy line was broken - it rarely was. The liftoff and then the creeping barrage was developed to keep artillery fire landing directly in front of the infantry as it advanced. Communications being impossible, the danger was that the barrage would move too fast - losing the protection - or too slow - killing with "friendly fire".
The set-piece battle with synchronized watches was the solution. Vimy Ridge was the first successful large scale battle using this tactic. Hugh Strong, an historian of that battle, claims morale in that particular battle was drastically enhanced by very intensive training that was able to anticipate problems.
However, casualties remained very high - it was possible to track enemy advances to land one's own barrages on them - landing shells right behind the enemy's creeping barrage. In fact, microphones were able to be planted to triangulate on the position of enemy guns and engage in counter-battery fire against those guns. And muzzle flashes of guns could be spotted. Eventually both sides could target enemy guns without having to fire a shell. 85-90% of guns were being wiped out in the first few minutes of any given battle.
Drills specific to a battle that could be anticipated in detail, training, synchronization even of the individual infantryman, the use of microphones, aerial maps, the airplane itself, and battlefield photography, made combat increasingly deadly.
Increased production also played a role in escalation:
Germans were able to increase production of guns and shells as were the British, but, 1914-1915 were marked by periods of trying to exhaust the enemy's shells in futile exchanges. By 1916 as production problems were in general solved, but gunners were short and hard to train. By 1917 this was solved and the artillery became a truly flexible arm once again - at a drastically higher firing rate.
At this point, effectively the economies were themselves in direct competition to produce more guns and shells to replace what was wiped out.
Counter-battery work was essential. Combinations of shells, tear gas, and later mustard gas (which was more persistent), were used to keep artillerymen wearing their gas masks, which drastically cut their effectiveness. Some, like the Canadians, refused to wear gas masks for this reason, and suffered terribly.
While early air spotters were famously gentlemanly to each other, by 1917 they were firing at each other and even throwing spears. A machine gun synchronized to the turn of the engine, based on crude battlefield prototypes rigged up by the British and captured, was a German innovation. Air combat got increasingly more deadly.
Mustard gas could "infect" the mud and infantry crawling through it were blinded, burned on skin, and develop horrendous blisters on groins, arms, legs. In July 1917 alone there were 15,000 British casualties due to this.
Men, mules and horses could actually drown in mud. Wood gun platforms, corduroy roads, etc., were used in the battle of Passchendale Ridge to create artificial solid ground.
Combining caterpillar treads from farm equipment with riveted construction from ships in 1917 yielded a weapon that could overcome some of the problems of the mud:
The first tanks crawled at 2 miles per hour, but they were frightening, and they solved the problem of how to cross mud, trenches, and avoid mustard infected and mined areas.
Between late 1914 and early 1918, the Western Front hardly moved. Neither side had had its line broken. Firepower and movement had not yet been combined into a strong enough combination to make warfare mobile. But in 1917 when Russia surrendered after the Russian Revolution, Germany moved many storm troopers to the Western front and the British 5th Army collapsed, and German shells began to fall on Paris. In March 1918 the German advance came to the outskirts of it.
By late April it looked like the allies might lose the war - except for Vimy Ridge which had been held for a year. On August 8 1918 the Canadians, holding the Ridge, and Australians and some British units, attacked in one massive short bombardment and wiped out nearly all the German guns. As infantry, guns, air all moved into action, the entire force moved more in one day than in the entire war. All the elements of the battle worked: the German line collapsed utterly.
The Hindenburg Line fell and the Canal du Nord was crossed - in Berlin Kaiser Wilhelm was told he had lost, and must now surrender. There were no advances in the fall as details of the surrender were negotiated, led to the 1918 Armistice on November 11, 1918.
The war was over. But a new form of warfare had emerged, mobility-driven, that would be mastered by the defeated Germans and deployed as their 1939 blitzkrieg, or lightning warfare, embodying all they had learned (the hard way) in 1918.
There were also impacts beyond the military, on the larger culture and perspective of European arts. Futurism, for instance, a school of painting that had been inspired by technological progress and many members of which had actually supported the war, more or less ceased to exist in the postwar disillusion.Trench warfare
Chemical weapons
Command and control
War of attrition
Air warfare
No man's land
Tanks
Mobility