BIDASOA, or VIDASOA, a small river which rises in the Western Pyrenees, in the valley of Baztan, and flows to the Atlantic near Cape Higués. On its left bank is the town of Fuenterahia, where the army of Charlemagne was defeated by the Gascons. On Oct. 7. 1813, Wellington, in his victorious career, crossed the Bidasoa at Irún, and the whole British army was encamped in France by the 10th of November.