Built in 1855 and armed with both 75mm and 155mm guns in retractible turrets. Largely de-manned in 1916 apart from its gun crews, it was captured on 25th Feb 1916 by a patrol of the 24th Brandenburg Reg. who managed to get into un-guarded tunnel entrance in the NE corner of the glacis. Its dominant position in the battlefield gave it great strategic importance and for eight months until October it was the focus of repeated attacks by the French who finally re-captured it on Oct 24th: estimates are that the French suffered over 100,000 casualties in their efforts to regain this fortress which in the end was abandoned by the Germans. On 8 May 1916 a grenade store inside the fort exploded and 679 German soldiers were killed, their remains being walled up in a gallery.