February 7, however, that and other
serious difficulties were overcome, and on the following day the
expedition captured Roanoke Island, and thus completely opened the whole
interior water-system of Albemarle and Pamlico sounds to the easy
approach of the Union fleet and forces.

From Roanoke Island as a base, minor expeditions within a short period
effected the destruction of the not very formidable fleet which the
enemy had been able to organize, and the reduction of Fort Macon and the
rebel defenses of Elizabeth City, New Berne, and other smaller places.
An eventual advance upon Goldsboro' formed part of the original plan;
but, before it could be executed, circumstances intervened effectually
to thwart that object.

While the gradual occupation of the North Carolina coast was going on,
two other expeditions of a similar nature were making steady progress.
One of them, under the direction of General Quincy A. Gillmore, carried
on a remarkable siege operation against Fort Pulaski, standing on an
isolated sea marsh at the mouth of the Savannah River. Here not only the
difficulties of approach, but the apparently insurmountable obstacle of
making the soft, unctuous mud sustain heavy batteries, was overcome, and
the fort compelled to surrender on April 11, after an effective
bombardment. The second was an expedition of nineteen ships, which,
within a few days during the month of March, without serious resistance,
occupied the whole remaining Atlantic coast southward as far as St.
Augustine.

When, at the outbreak of the rebellion, the navy-yard at Norfolk,
Virginia, had to be abandoned to the enemy, the destruction at that time
attempted by Commodore Paulding remained very incomplete. Among the
vessels set on fire, the screw-frigate _Merrimac_, which had been
scuttled, was burned only to the water's edge, leaving her hull and
machinery entirely uninjured. In due time she was raised by the
Confederates, covered with a sloping roof of railroad iron, provided
with a huge wedge-shaped prow of cast iron, and armed with a formidable
battery of ten guns. Secret information came to the Navy Department of
the progress of this work, and such a possibility was kept in mind by
the board of officers that decided upon the construction of the three
experimental ironclads in September, 1861.

The particular one of these three especially intended for this peculiar
emergency was a ship of entirely novel design, made by the celebrated