During the war, trenches evolved from muddy ditches to complicated fortifications. A great deal of thought went into their construction. This section will look at some of the common characteristics shared by all trenches.

Each side had a front line of trenches, following each other from the North Sea to the Swiss border. Between the two front lines was an area of devastated wasteland between twenty-five and several hundred metres deep known as No Man’s Land (Figs.3 and 13). The front lines bent and twisted with the lie of the land in order to take advantage of ridges and canals. They also zigzagged to contain shrapnel and explosions, and so a bullet could not travel the length of the trench. Raiders had to fight round every corner. Barbed wire doors that could be opened and shut also slowed down raiders. The zigzags also allowed attackers to be fired at from three sides and sometimes firing bays were dug out into no man’s land to exploit this further (Fig.3).

Earth dug out to construct the trench was piled up to form the parapet and parados, increasing protection from enemy fire. It was preferred for a trench to be 2.5 metres deep, so that a man could stand up without revealing his head (Fig.2). However, mud, rock and corpses often halted attempts to deepen them. To stop the vibrations of shellfire from letting earth from the parapet fall back into the trench, sandbags, corrugated iron or wickerwork were used to strengthen the walls. When it began to rain, mud and large pools of water became a problem. To remedy this, the British in particular began using duckboards.

On the side of the trench facing the enemy, a firestep allowed sentries at night, soldiers at dawn, and defending soldiers to view and fire at the enemy. It was not often used during the day for viewing because of the risk of snipers. Instead, a periscope was more favourable (Fig.14).

The German trenches were normally far superior with elaborate bunkers and concrete-lined shelters. They could be up to 50 metres deep with several levels with sick bays, kitchens and rooms for sleeping in. Even the lower ranks had good quarters with real beds and, often, electric lighting. One French soldier called a captured German trench "really plush."

The British trenches on the other hand were not as good . The generals believed that trenches were temporary fortifications, and would cease to be used the next spring when the war of movement returned. They did not want their men to get too comfortable. This precedent clearly didn’t apply to the generals themselves in their secluded chateaus behind the front. So the British soldiers had to live in dugouts scraped out of the sides of the trench. These might be strengthened with sandbags and possibly corrugated iron, which completed the inadequate protection. Within these dugouts were planks or doors that served as a bed, if the man was lucky. Officers faired better with beds, tables, a chair, and a sentry to guard them at night. But the difference was slight, and in no way were they up to German standards. The overall difference in comfort compared with the enemy was an important blow to British morale.

Behind the front line were the reserve trenches where reinforcements waited (Fig.3). They could be used if the front line was taken. Behind the reserves were the fortified villages and artillery. These areas were only marginally less deadly than the front and reserve lines as they were often targeted by enemy artillery.

The arteries linking all these were the communication trenches which ran from the front line to a point far enough back where it was safe for a man to walk in the open. Supplies were carried to the front, and in the other direction were rushed the wounded. Many did not make it in time, and died on the floor of the communication trenches.