The long years of the struggle for throwing off the dominions of Spain wrought a great change in Mexican mining, and even when independence was accomplished, the warring revolutionary factions of a country divided against itself destroyed all sense of security, alienated the labour, and so mining fell into disuse, and the mines into ruins. The history of the great Guanajuato silver mines is typical of the effect political conditions exercised upon this industry. The great output of silver from the Valenciana mine--300 million dollars during the last half of the eighteenth century--fell, after the first decade of the nineteenth, to insignificant proportions. The city was attacked in 1810, when in the zenith of her production, by the revolutionary army of the Republicans under Hidalgo, the famous instigator of independence. Sanguinary struggles took place in the city, which fell, and with it the mining industry. Work was stopped; the waters flooded the shafts and galleries, general lawlessness took the place of order, and bands of armed robbers helped themselves at will to the silver, and made forced loans upon the community. Indeed, at the great mining centres throughout the country, Mexican mine buildings resemble fortifications rather than the structures of a peaceable industry; those which were constructed during those turbulent times. Battlemented walls and loopholes give some of these places the appearance of the stronghold of robber barons of the Middle Ages, and remind the traveller, under the peaceful _regime_ of to-day, how rapid has been the country's progress.