Since the time of Vauban the improvements in attack have not kept pace with the increased means of defence.

Moreover, these examples are taken from the sieges of towns defended mainly by old and antiquated works, and entirely incapable of offering the same resistance as detached fortifications, with all the modern improvements.
The value of fortifications, as land defences, is sufficiently proved by showing their general capability of resisting an invader, even for a limited period; thus affording us time and opportunity to provide other means of security.

But it must not be inferred that forts besieged _en regle_ will necessarily fall after so many days.

Such is far from being the case.

The besieged have usually great advantages over the besiegers; and unless the latter are vastly superior in number, or the work is of a very inferior character, or the garrison is destitute of the requisite means and energy to resist an attack, they will not be taken.
Mezieres was not taken in 1520; nor Marseilles in 1524; nor Peronne in 1536; nor Landrecies in 1543; nor Metz in 1552; nor Montauban in 1621; nor Lerida in 1647; nor Maestricht in 1676; nor Vienna in 1529, and again in 1683; nor Turin in 1706; nor Conde in 1744; nor Lille in 1792; nor Landau in 1793; nor Ulm in 1800; nor Saragossa in 1808; nor Burgos in 1812.