C. S. Forester 
The Gun [EPUB ebook] 

Abandoned by the retreating Spanish Army during the Peninsular war, the gun was a bronze cannon, weighing three tons. When a group of Spanish partisans come across it two years later they see in it a chance for victory against the French. But first they must take it a hundred miles across the mountains, with nothing but a handful of donkeys and half-starved oxen to haul it. On its epic journey over the mountains, the ornamented bronze cannon begins to gain almost mystical significance for the ever-swelling force that surrounds it. With the gun going on before them they are no longer a mere band of Spanish irregulars, they are an army. With the might of the gun on their side they can take on the cream of Napoleon's troops, they can march openly across the plains, they can batter great fortresses into subjection…