How trenches were made
During World War 1 trench building encompassed digging the trench by hand or, for the luckier soldiers, using shovels. Reinforcing was then done on the sides of the trenches with wood, tree posts, and sand bags. These trenches were usually built at night, before the enemy encroached upon the area.
The trenches used in World War I were about 2.13 metres deep and 1.82 metres wide. The rear of the trench was made up of thick sand bags that were used to absorb shell pieces and bullets. The trenches ran for 700 kilometres and were dug in a zigzag manner.
Now
Now you can just used a big digger if you wanted to make a trench
Mortars
Vehicles
Info: http://mentalfloss.com/article/31882/12-technological-advancements-world-war-i
Tavin Honeyghan 