The gases are used for the first time by the Germans in 1917 in Ypres
The industrial war has worked out the chemical weapon and has just completed the dehumanization of the engagements. The gas is not a completely invisible enemy because it emits a low greenish fluorescence which increases terrifying dimension by it.
The First World War carries to their paroxysm the universalization of the ambitions, the tensions for the installation of the chart of Europe, and military and ideological competition between the States, which already strongly marked the European history after 1870.
But, for the generation of 1914-1918, the Great War signs a change of time, the disappearance of the old order, the true end of the XIXe century.
In many fields, the war brutally brings its batch of innovations - military technology, place of the women and the workmen in the company, wide intervention of the State - and of upheavals, with the proletarian revolution, in Russia. The innovation is due also to the fact that it is, very whole, the war of the nations, these nations that the XIX E century consolidated and who invested in this conflict their identity and their honor.
It was as much the war of the patriots, as it attests the extent of manpower and the undergone losses, which the people entered resigned but sure of their right good, and sometimes also enthusiastic, the families accompanying by singing fathers, son and brothers who left.