Trench warfare was Intorduced in World War 1. By World War 2, really the end of ww1 on. they were outdated due to the use of tanks and their ability to roll over the barbed wire and trenches.
The United States during World War 2. The development is known as the Manhattan Project
The first year it was a war of pushing the enemy and then being pushed back. The Germans pushed a little too much and had to retreat really fast, but they received the order not to retreat after the former German borders. So, they built trenches on elevated ground and waited for the allies. After that it was just hiding in the trenches, waiting for the next assault to come or to be announced. Most of the dead perished because of the bad hygiene, or just lucky potshots.
Thousands of trenches were constructed during World War 1. Most had names for operational purposes but few names are remembered. EDIT: Are you thinking of World War 2 and the Maginot Line?
Front-line trenches were not dug in straight lines. Otherwise, if the enemy had a successive offensive, and got into your trenches, they could shoot straight along the line. The French tended to build zig-zag trenches. However, the British Army preferred a system where each trench was dug with alternate fire-bays and traverses. Whereas fire-bays were straight sections of trenches, traverses were built at angles. This limited the effect of enfilade fire or shell-burst
It wasn't built during a war, it was after World War II.
Thessaloniki, or Salonika.
Many things made it possible to fire from the trenches. Mortars and field artillery were often fired from trenches. Trenches usually had berms (low dirt walls) built in front of them with firing positions along the top of the berm. Trenches sometimes had benches or ladders for gunners and snipers.
Trench warfare used several different types of trenches. Firing trenches were used by soldiers to protect themselves while firing their weapons at their enemy. Cover trenches were often built next to the firing trenches as a second line of defense in case the enemy captured the firing trench. Support trenches were used as rest areas for off-duty troops, who sometimes lived in dugouts excavated in the sides of the trench. A network of reserve and communications trenches was used to bring supplies and fresh troops to the front.
It was called the none of the viro
To prtect the army from getting shot
After the war the trenches went away as the land returned to its original uses, but I found a couple of them left that you can visit. One is Vieil Armand in Alsace, and the trenches were mostly carved in stone so they are well preserved. Also, World War 1 trenches in the Meuse have been restored to their original condition so that people can visit them. The German trenches there were built with concrete reinforcements, but the French trenches had filled in over the years and had to be dug out again.
They had to get there before the other side did, so that they could get an advance into making their trench, so before the other side come, they will be ready will their trenches!
by digging trenches and connecting the rivers
they built trenches for procetion and they used it as a base.
The trenches were called saps and the people who dug them were called sappers.
The United States during World War 2. The development is known as the Manhattan Project
The trenches on the western front were built in a more or less continuous line from the North Sea all the way to the border of Switzerland. A distance of about 750 km; considering that both sides used multiple trench lines, plush support trenches, and zigzags across the landscape there would have been several thousand kilometres of trenches being used by either side at any given time.