Field counterpart of the garrison cannon was the
siege gun—the "battering cannon" of the old days, mounted upon a
two-wheeled siege or "traveling" carriage that could be moved about in
field terrain. Whereas the purpose of the garrison cannon was to destroy
the attacker and his materiel, the siege cannon was intended to destroy
the fort. Calibers ranged from 3- to 42-pounders in eighteenth century
British tables, but the 18- and 24-pounders seem to have been the most
widely used for siege operations.
FIGURE 32—SPANISH EIGHTEENTH CENTURY SIEGE CARRIAGE.
The siege carriage closely resembled the field gun
carriage, but was much more massive, as may be seen from these
comparative figures drawn from eighteenth century British
|24-pounder field carriage
|24-pounder siege carriage
|9 feet long
||Length of cheek
||Thickness of cheek
Heavy siege guns were elevated with quoins, and
elevation was restricted to 12° or less, which was about the same as
United States siege carriages permitted in 1861. It was considered ample
for these flat trajectory pieces.
Both field and siege carriages were pulled over long
distances by lifting the trail to a horse- or ox-drawn limber; a hole in
the trail transom seated on an iron bolt or pintle on the two-wheeled
limber. Some late eighteenth century field and siege carriages had a
second pair of trunnion holes a couple of feet back from the regular
holes, and the cannon was shifted to the rear holes where the weight was
better distributed for traveling. The United States siege carriage of
the 1860's had no extra trunnion holes, but a "traveling beds" was
provided where the gun was cradled in position 2 or 3 feet back of its
firing position. A well-drilled gun crew could make the shift very
rapidly, using a lifting jack, a few rollers, blocks, and chocks. When
there was danger of straining or breaking the gun carriage, however,
massive block carriages, sling carts, or wagons were used to carry the
Sling wagons were of necessity used for transport in
siege operations when the guns were to be mounted on barbette
(traversing platform) carriages (fig. 10). Emplacing the barbette
carriage called for construction of a massive, level subplatform, but it
also eliminated the old need for the gunner to chalk the location of his
wheels in order to return his gun to the proper firing position after
The Federal sieges of Forts Pulaski and Sumter were
highly complicated engineering operations that involved landing
tremendously heavy ordnance (the 300-pounder Parrott weighed 13 tons)
through the surf, moving the big guns over very difficult terrain and,
in some cases, building roads over the marshes and driving foundation
piles for the gun emplacements.
The heavy caliber Parrotts trained on Fort Sumter
were in batteries from 1,750 to 4,290 yards distant from their target.
They were very accurate, but their endurance was an uncertain factor.
The notorious "Swamp Angel," for instance, burst after 36 rounds.
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