21 September 1914,
167 Basques died in northern France, near the village of Craonne. It was the bloodiest day for the Basques during World War I. During the Great War thousands of Basques deserted and fled to Hego Euskal Herria or America. However, this war was traumatic, as nearly 6,000 Basques died on the front and thousands were maimed forever. The leaders and priests claimed the death of the dead for the homeland, for France, strengthening the assimilation of Northern Basque society.
Source:
Eneko Bidegain Conference - First World War and the Basque Country.