Under the Red Robe by Stanley J. Weyman

So that was their plan. Two or three hours to the southward, the long, white, glittering wall stretched east and west above the brown woods. Beyond that lay Spain. Once across the border, I might be detained, if no worse happened to me, as a prisoner of war; for we were then at war with Spain on the Italian side. Or I might be handed over to one of the savage bands, half smugglers, half brigands, that held the passes; or be delivered, worse fate of all, into the power of the French exiles, of whom some would be likely to recognise me and cut my throat.

'It is a long way into Spain,' I muttered, watching in a kind of fascination Clon handling his pistols.