to come out at night to re-supply troops in the front line. Located below Flanders and dug over a period of four months by 171st Tunnelling Company, the Royal Engineers used I beams and reclaimed railway line in a D-type sett structure. This was then further reinforced, using stepped wooden horizontal beams. Operational use Vampire became operational from early April 1918, first housing the 100th Brigade of the British 33rd Division, then the 16th King's Royal Rifle Corps and then the 9th Battalion Highland Light Infantry Regiment. But after only a few weeks, the dugout was lost when the Germans undertook the Battle of the Lys in April 1918. It was recaptured in September 1918, when its last occupants became the 2nd Battalion of the Worcestershire Regiment. When Vampire was excavated in 2008 (see below), the archaeologists found many signs inside the dugout of occupation by the British, but few from the Germans. There was a total absence of metal bed structures, suggesting that the British had had little time to fit out the dugout before it was overrun. The researchers first estimated that the dugout would measure by , but tunnels were eventually found to cover an area of by . Designed by the Royal Engineers to house 50 men, the researchers now estimate that Vampire may have been used by at least 300 soldiers. Whether Vampire was extended by the British or the Germans will take further investigation, although signs of construction in progress have been found throughout the workings. Occupying units 100 Brigade Headquarters, 33rd Division 16th Battalion (Church Lads Brigade) King's Royal Rifle Corps 1st/9th Battalion Highland Light Infantry 2nd Battalion Worcestershire Regiment These three battalions were the three constituent battalions of 100 Brigade Vampire after the war: 1920 onwards After the cessation of hostilities in November 1918, all deep dugouts including Vampire were abandoned. When the troops left within weeks of the war ending, the subterranean structures were slowly submerged. After the removal of known munitions at the surface by military clean-up teams, the Belgian locals returned from 1920, recovering the upper sections of the wooden entrance steps for heat and building, and then filled the main shafts with rubble to enable the land to be returned to farming. Locals also resumed extracting the local blue clay for commercial purposes, mainly in brickworks. The gradual expansion of the commercial extraction activities by the Terca Zonnebeke