Statistics for occurrence #1 of “Boston Harbor” in chapter 7 of Historic leaves, volume 8, April, 1909 - January, 1910:

... where they marched to the Powder House. The 250 half-barrels of powder which the magazine contained were speedily transferred to the boats and removed to Castle William (now Fort Independence), in Boston Harbor . A detachment of troops also visited Cambridge, and carried off two field pieces which they found there. The news of the seizure of the powder spread with great rapidity, and on the following mor...
Max. Freq. Min. Freq.
Entity Corpus Doc Corpus Doc  
Boston Harbor (Massachusetts, United States) 627 4 1 0 0 user votes
Boston Harbor (New Hampshire, United States) 0 0 0 0 0 user votes
Boston Harbor (Washington, United States) 0 0 0 0 0 user votes
Boston Harbor (Washington, United States) 0 0 0 0 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.