Arrayed in front of the course of the River Nivelle, whose route was marked by a series of hills on which the French had built strong defensive positions or redoubts, was the French army under Marshal Soult. 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 20 miles. With only 60,000 men, Soult was stretched to an almost impossible point. This also means that he could not hold troops back as reserves, something which may have turned the tide of the battle. As Soult moved back to his base at Bayonne, his position strengthened but he was not quick enough and Wellington caught him up.