Statistics for occurrence #1 of “Fort Johnson” in chapter 1.1 of Robert Underwood Johnson, Clarence Clough Buell, Battles and Leaders of the Civil War. Volume 4.:
...defend the approach to Fort Sumter.
It was intended for eleven guns, and was not entirely finished, even as originally designed.
6. A small work (Fort Ripley) equidistant from Castle Pinckney and Fort Johnson , not yet armed, but planned for four heavy guns en barbette [only two put in.--editors]. 7. Castle Pinckney, armed with nine 24-pounders and one 24-pounder rifled, a work of no value for the defense ...
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