Historic England: First World War Northumbrian practice trenches, as revealed by aerial reconnaissance.
The carnage and misery of trench warfare is for many the abiding image of the First World War. Practice trenches, built by soldiers in training, are among the more emphatic monuments to that conflict to remain visible in the English landscape. A complex of such sites in Northumberland throws light on the achievements of one such group of soldiers, known as the 1st Tyneside Pioneers.
Further information here.