Regina Trench (Staufen Riegel) was a German trench dug along the north-facing slope of a ridge running from north-west of the village of Le Sars, south-westwards to Stuff Redoubt (Staufenfeste), close to the German fortifications at Thiepval on the Somme battlefield. It was the longest such trench on the German front during the First World War. Attacked several times by the Canadian Corps during the Battle of the Ancre Heights, the 5th Canadian Brigade briefly controlled a section of the trench on 1 October but was repulsed by counter-attacks of the German Marine Brigade (equivalent to an army division), which had been brought from the Belgian coast. An attack on 8 October, by the 1st Canadian Division and the 3rd Canadian Division on Regina Trench also failed.
On 21 October, the 4th Canadian Division attacked the western portion of Regina Trench, as the 18th Division, 25th Division and the 39th Division of II Corps, attacked the part further west (known as Stuff Trench to the British). The Canadians met little opposition and gained the objective, as the II Corps divisions captured Stuff Trench in thirty minutes, giving the British control of the Thiepval Ridge. Three counter-attacks were repulsed by the Canadians and by 22 October, more than a thousand Germans had been taken prisoner. The east end of the trench was captured by the 4th Canadian Division during the night of 10/11 November.