After the Allied siege of San Sebastian, Wellington's 80,000 British, Portuguese and Spanish troops (20,000 of the Spaniards were untried in battle) were in hot pursuit of Marshal Soult who had 60,000 men to place in a 20-mile perimeter.

In the Battle of San Marcial on 31 August, Soult failed to break through the Spanish defences in his final attempt to relieve the siege.

The French army then fell back to defend the Bidassoa River, which forms the French-Spanish frontier near the coast.

At dawn on 7 October, the Anglo-Allied army overran the French river defences in the Battle of the Bidassoa in a surprise crossing.

Soult's lines stretched from the shores of the Atlantic on the French right flank to the snow-covered pass of Roncesvalles on the left, a perimeter of about twenty miles.

If the French defences on La Rhune could be taken Soult's position would become very dangerous as it would open him to attack from all elements of the British three-point pincer plan.

So, Wellington ordered that the British left (attacking the French right) would be led by Sir John Hope and would involve the 1st and 5th Divisions as well as Freire's Spaniards.

News of the victory reached London at the same time as reports of the Liberation of Hanover by Allied forces, leading to a double triumph.