Soult was expecting the Allied offensive across the Bidassoa river but was not sure where it would come. He considered the lower reaches to be impassable and therefore assigned only Reille's corps of 6,500 men to defend this area. Wellington's intelligence officers had discovered that the river was 20 feet deep at full tide but at very low tides it fell by 16 feet. At 8am on the 7th the tide was exceptionally low and the Fifth Division crossed the estuary, driving back the sentries. The Fifth were soon supported by the First Division and a Spanish Division. Reille could not concentrate his troops and had to withdraw. With his flank thus turned Soult had no choice but to withdraw the whole of his force losing their artillery and most of their baggage train.
The second prong attack at Vera was carried out by the British Light Division and two Spanish Divisions. Heavily out numbered, fighting their way up steep slopes against strong fortifications around the hill called Le Grande Rhune. The French were driven back across the whole sector, losing their artillery. The next day the garrison of Le Grande Rhune, now left isolated, surrendered.

Bidassoa river estuary, north-western Pyrenees, Biscay coast and for 9 miles inland. (France)

French Army of Spain [Soult]

Number engaged :

41,500

Casualties :

1,750 (4.22%)

British Peninsular Army

Number engaged :

24,000

Casualties :

1,515 (6.31%)