Statistics for occurrence #1 of “Fortress Monroe” in year 1861, month June, day 3 of Rebellion Record: a Diary of American Events, Diary from December 17, 1860 - April 30, 1864:

...a proclamation announcing to the soldiers that they would soon meet the insurgents. --(Doc. 230.) The First Regiment Scott Life Guard and the Third Regiment N. Y. S. V., left New York city for Fortress Monroe .--(Doc. 231.)
...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Fortress Monroe (Virginia, United States) 7,630 215 276 21 0 user votes

† This entity has been selected by the automated classifier as the most likely match in this context. It may or may not be the correct match.