g the Mississippi and other
waterways leading into the heart of the Confederacy. To make the
blockade effective and cut off the South from the rest of the world,
the Federal Government unhesitatingly applied the doctrine of
"continuous voyage," seizing and condemning neutral ships even when
bound from England to Bermuda or the Bahamas, if their cargo was
ultimately destined for Southern ports. The doctrine was declared
inapplicable when the last leg of the journey was by land,[1] doubtless
because there was little danger of heavy traffic across the Mexican
frontier. Blockade runners continued to pour goods into the South
until the fall of Fort Fisher in 1865; but as the blockade became
more stringent, it crippled the finances of the Confederacy, shut
out foodstuffs and munitions, and shortened, if it did not even
have a decisive effect in winning the war.

[Footnote 1: Peterhoff Case, 1866 (5 Wall, 28).]

To meet these measures the South was at first practically without
naval resources, and had to turn at once to new methods of war. Its
first move was to convert the steam frigate _Merrimac_, captured
half-burned with the Norfolk Navy Yard, into an ironclad ram. A
casemate of 4 inches of iron over 22 inches of wood, sloping 35
degrees from the vertical, was extended over 178 feet, or about
two-thirds of her hull. Beyond this structure the decks were awash.
The _Merrimac_ had an armament of 6 smoothbores and 4 rifles, two
of the latter being pivot-guns at bow and stern, and a 1500-lb.
cast-iron beak or ram. With her heavy load of guns and armor she
drew 22 feet aft and could work up a speed of barely 5 knots.

Faced with this danger, the North hurriedly adopted Ericsson's
plan for the _Monitor_,[2] which was contracted for on October
4, 1861, and launched after 100 days. Old marlin-spike seamen
pooh-poohed this "cheesebox on a raft." As a naval officer said,
it might properly be worshiped by its designer, for it was an image
of nothing in the heavens above, or the earth beneath, or the waters
under the earth. It consisted of a revolving turret with 8-inch
armor and two 11-inch smoothbore guns, set on a raft-like structure
142 feet in length by 41-1/2 feet in beam, projecting at bow, stern,
and sides beyond a flat-bottomed lower hull. Though unseaworthy,
the _Monitor_ maneuvered quickly and drew only 10-1/2 feet. She
was first ordered to the Gulf, but on March 6 this destination
was suddenly changed to the Chesapeake.