During the First World War (1914–1918), the construction and maintenance of the Western Front in North-west Europe required huge quantities of timber. Although archaeological investigations regularly uncover well-preserved wooden structures and objects, studies of the timber's provenance are rare. The authors combine archival research with wood-species identification and tree-ring analysis of a large assemblage of wooden objects excavated from former trenches on the Western Front. The results show that most objects and structures were made using fast-growing European species, with evidence for the small-scale but continuous importation of North American timber.