Statistics for occurrence #1 of “Harper's Ferry” in page 96 of John G. Nicolay, The Outbreak of Rebellion:

... Under these circumstances occurred the sudden fall of Sumter, the President's proclamation, the secession of Virginia, and the immediate movement of Governor Letcher's State forces against both Harper's Ferry and Gosport. As a preliminary act, he thought to absolutely prevent the escape of the ships by obstructing Elizabeth River with small sunken vessels. The device did not completely succeed, though...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Harper's Ferry (West Virginia, United States) 10,974 70 304 0 0 user votes

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