a contest maintained against batteries manned with
soldiers instructed by officers of skill and science, not only in
working the guns, but in the endless duty of detail necessary for
keeping the whole of an artillery material in a proper state of
formidable efficiency."

_San Juan d'Ulloa._--The following facts, relative to the attack on San
Juan d'Ulloa by the French, in 1838, are drawn principally from the
report of a French engineer officer who was one of the expedition.

The French fleet consisted of four ships, carrying one hundred and
eighty-eight guns, two armed steamboats, and two bomb-ketches with four
large mortars. The whole number of guns, of whatever description, found
in the fort was one hundred and eighty-seven; a large portion of these,
however, were for land defence. (Fig. 37.)

When the French vessels were towed into the position selected for the
attack, "it was lucky for us," says the French officer in his report,
"that the Mexicans did not disturb this operation, which lasted nearly
two hours, and that they permitted us to commence the fire." "We were
exposed to the fire of one twenty-four-pounder, five sixteen-pounders,
seven twelve-pounders, one eight-pounder, and five eighteen-pounder
carronades--_in all nineteen pieces only_." If these be converted into
equivalent twenty-four-pounders, in proportion to the weight of the
balls, the whole nineteen guns will be _less than twelve twenty-four
pounders_. This estimate is much too great, for it allows three
eight-pounders to be equal to one twenty-four-pounder, and each of the
eighteen-pounder carronades to be three quarters the power of a long
twenty-four-pounder; whereas, at the distance at which the parties were
engaged, these small pieces were nearly harmless. Two of the powder
magazines, from not being bomb-proof, were blown up during the
engagement, by which three of the nineteen guns on the water front of
the castle were dismounted; thus reducing the land force to _an
equivalent of ten twenty-four-pounders_. The other sixteen guns were
still effective when abandoned by the Mexicans. The cannonade and
bombardment continued about six hours, eight thousand two hundred and
fifty shot and shells being fired at the fort by the French. The
principal injury received by the work was from the explosion of the
powder magazine. But very few guns were dismounted by the fire of the
French ships, and only three of these on the water front. The details of
the