塹壕
Until 1914, artillery generally fired over open sights at visible targets, the largest unit accustomed to firing at a single target was the artillery regiment or brigade. One innovation brought about by the adoption of trench warfare was the barrage—a term first used in the battle of Neuve Chapelle in 1915. Trench warfare had created the need for indirect fire, with the use of observers, more sophisticated artillery fire plans, and an increasingly scientific approach to gunnery, where artillerymen had to use increasingly complicated calculations to lay the guns. Individual guns were aimed so that their fall of shot was coordinated with others to form a pattern; in the case of a barrage, the pattern was a line.