Why did trenches develop and what were their key features?

Trenchers became increasingly complex and were mainly in three parts; the front line, reserve lines and support lines. Troops would rotate between reserve lines on the front line every so often to get some rest away from the fighting. Trenches became part of huge networks of these lines and spanned for 100s of miles. They were also built in zigzag formations as to prevent mass casualties along the whole trench if it by an artillery shell, and also to make it a more difficult target for gunners.The area between opposing trenches was known as no man's land and was an extremely dangerous place to be. This area was also often line with the rows of barbed wire to make it harder for trend rate to take place, by obstructing the path of soldiers.

Trenchers had to be deep enough so that the opposition could not shoot men walking in the trenches but soldiers also had to be able to shoot out of them. Fire steps were planks jutting out from the side of the trench wall, and soldiers would raise themselves up and shoot, just looking over the trench wall. The trench walls were reinforced with sandbags for bullet production and would support the trench to stop the trench walls collapsing in. The parapet was a raised part of earth at the front of the trench, where guns were rested. This area was lined with barbed wire for protection from grades and sandbags as further protection. As rain water often collated at the base of the trench making it unhygienic and difficult to walk in, soldiers who constantly walked in the mud and water became infected with gangrene, which resulted in their infected limbs having to be amputated. Because of this raised platform is made of wood, known as duckboards, what are used as a dryer safe area to walk, with the mud and water below. Dugouts were storage and resting areas dug into the back of the trench. British dugouts were relatively primitive, with no or less proper beds, and no proper eating areas. On the other hand, German dugouts were far more luxurious with bunkbeds, coffee tables and, in some places, concrete flooring. The British idea was that the soldiers shouldn't get too comfortable, as they were trying to fight a war of advancement and movement and were not planning on using the trenches for very long, Whereas the Germans war fighting more of a defensive war. Latrines were not complex at all, and in most circumstances where a hole in the ground, or a bucket. In the summer, the smell of the latrines was strong and sickening. However, as the war progressed trenches became more advanced, and many of them have survived until even today.