A secret underground tunnel was discovered last year by archaeologists near the Belgium village of Zonnebeke and it is now being excavated.

The hidden shelter, known as Vampire Dugout, served as an underground headquarters for the British during World War I. The dugout was apparently named after soldiers who’s mission was to come out at night to re-supply the front lines.

Constructed during the Battle of Passchendaele (1917), officially known as the Third Battle of Ypres, the shelter is full of water that needs to be first pumped out.

According to an earlier BBC news report titled, Uncovering the secrets of Ypres, the dugout was held by the Allies until the 1918 German offensive, briefly occupied by German forces and then recaptured by the British toward the end of the war.

Because the shelter was flooded and buried for 90 years, there is a strong likelihood that the lack of light and oxygen will have nearly perfectly preserved anything that was left within the dugout. Of that there are high hopes.

The embedded BBC news video provides more details including interesting video of the entrance to the tunnel, which is now open.