For the weeks that followed, Soult could only look on while San Sebastian and Pampeluna fell. Then the allied outposts were advanced to the slopes looking down on France and the distant sea. It is recorded that the Highlanders of Hill's division, like Xenophon's Greeks 2000 years before them, broke into cheers when they caught their first glimpse of the sea, the great, wrinkled, azure-tinted floor, flecked with white sails. It was "the way home!" Bearn and Gascony and Languedoc lay stretched like a map under their feet. But the weather was bitter, the snow lay thick in the passes, sentinels were frozen at the outposts, and a curious stream of desertions began. The warm plains of sunny France tempted the half-frozen troops, and Southey computes, with an arithmetical precision which is half-humorous, that the average weekly proportion of desertions was 25 Spaniards, 15 Irish, 12 English, 6 Scotch, and half a Portuguese! One indignant English colonel drew up his regiment on parade, and told the men that "if any of them wanted to join the French they had better do so at once. He gave them free leave. He wouldn't have men in the regiment who wished to join the enemy!" Meanwhile Soult was trying to construct on French soil lines of defence as mighty as those of Wellington at Torres Vedras; and on October 7, Wellington pushed his left across the Bidassoa, the stream that marks the boundaries of Spain and France. On the French side the hills rise to a great height. One huge shoulder, called La Rhune, commands the whole stream; another lofty ridge, called the "Boar's Back," offered almost equal facilities for defence. The only road that crossed the hills rose steeply, with sharp zigzags, and for weeks the French had toiled to make the whole position impregnable. The British soldiers had watched while the mountain sides were scarred with trenches, and the road was blocked with abattis, and redoubt rose above redoubt like a gigantic staircase climbing the sky. The Bidassoa at its mouth is wide, and the tides rose sixteen feet.