They were the western front. But the different trenches were front line trenches, communication trenches.
Western Front
Tall towers with curving sides that taper at the top.
The Mediterranean Sea, the English Channel, the North Atlantic Ocean. France is not surrounded on all sides by water.
The Basque area of France ("Pays Basque") is in the South-West of the country. The Basque area extends on both sides of the French-Spanish border, the larger part is in Spain.
Metropolitan France is often referred to a 'l'Hexagone, and is indeed roughly hexagonal in shape.
because the outline of France is like the shape of a hexagon
The soldiers themselves dug out the trenches.
The Germans were tring to conquer France. The Allies were trying to stop them. Both sides just kept on going North, making trenches to stop the other side, until both sides reached the sea.
The trenches were filled with water because when it rained if they didn't pile the sides up with sand and supported the sides would slip and make mud puddles at the bottom of the trench.
Wood, packed dirt and sandbags held up the sides of cruder trenches. More intricate ones had concrete siding.
Flanders ("les Flandres" in French) are located both sides of the French and Belgian border.
By mid- to end-October 1914, the line of trenches stretched from the border of neutral Switzerland, through France and Belgium to the North Sea. The lines of the trenches would move forwards and backwards throughout the war, during offensives (or attacks) by both sides. In some areas, at the beginning of the war, trenches were no more than shallow ditches, or even interconnected shell holes. As the war of movement came to an end and the war of attrition began, the trenches became more and more advanced, both in depth, breadth and forms of construction. Materials commonly used to support the trenches (it's important to note that the majority of trenches were dug into the clay soil of that part of France) were wood, as in the limbs of trees and planks, sheet metal, sand bags, and concrete.
I assume the question is about the trenches used in World War I? Both sides of the conflict reached a stalemate and dug protective trenches. The number of soldiers killed and maimed (on both sides) was tremendous and proved the futility and waste of warfare, as frontal attacks moved the front back and forth.
Silent Night
This prevents the sides of the trenches from collapsing, covering (and suffocating) anyone inside the trench. Trenches can collapse due to artillery fire or merely from shifting soil (often due to rain or other weather).
Trench foot and dysentery were the major conditions found in the trenches. Filled with standing stagnant cold water, soldiers on both sides suffered from foot rot and lack of sanitation.
It was during World War 1 that fighting stopped in the trenches and both fighting sides played football. It was called the Christmas Truce and took place in 1914.
trenches... trench warfare.... what exactly do you need?