Trench warfare
Trench warfare occurred when a revolution in firepower was not matched by similar advances in mobility, resulting in a grueling form of warfare in which the defender held the advantage. On the Western Front in 1914–1918, both sides constructed elaborate trench, underground, and dugout systems opposing each other along a front, protected from assault by barbed wire, mines, camouflaged trapping pits, and other obstacles. The area between opposing trench lines (known as "no man's land") was fully exposed to artillery fire from both sides. Attacks, even if successful, often sustained severe casualties.
Boezinge
In the 1990s an original British trench system ("Yorkshire Trench") was discovered by amateur archaeologists, on the site of an industrial estate near the village. Yorkshire Trench was a first line trench for about one year between summer or autumn 1916 until the summer of 1917. In spring of 1917, 173rd Tunnelling Company added a deep dugout to the existing trench. The completed Yorkshire Trench dugout then served as headquarters for the 13th and 16th Battalions of the Royal Welch Fusiliers at the start of the Battle of Passchendaele later that year. The BEF had decided to carry out all operations in the offensive of summer 1917 from deep dugouts. East of the Ypres Canal in the close vicinity of Yorkshire Trench there were several more dugouts, seven of which - all south and southeast of Yorkshire Trench - were finished by the 173rd or 179th Tunnelling Companies. Of these, "Yorkshire Trench", "Butt 18", "Nile Trench" and "Heading Lane Dugout" were double battalion headquarters, "Bridge 6" was a brigade headquarters, and" Lancashire Farm Dugout" contained two battalion and two brigade headquarters. The condition of the ground made digging the deep dugouts extremely difficult and dangerous. Work had to be carried out silently and secretly, facing an observant enemy who was only a few hundred metres away. About 180 dugout sites have been located in the Ypres Salient and in the 1990s some of them were entered, at least in part. 
Yorkshire Trench was rediscovered by amateur archaeologists and systematically excavated in 1998. Although the area is now part of a large industrial estate, the location was opened to the public in 2003 Yorkshire Trench is located close to the John McCrae memorial site at Essex Farm.The estate was destroyed during the first world war in July 1917 and rebuilt after the war.