Statistics for occurrence #1 of “Drewry's Bluff” in chapter 12 of The Photographic History of The Civil War: in ten volumes, Thousands of Scenes Photographed 1861-65, with Text by many Special Authorities, Volume 5: Forts and Artillery.:
...rated the lower river from the upper.
If the Federals could cut through this neck, they could avoid the Confederate works and move on up the river by boat as far as the works at Chaffin's Bluff and Drewry's Bluff . Captain Peter S. Michie, of the United States Engineers, later a brigadier-general, was detailed to dig a canal through at Dutch Gap.
This would cut off four and a half miles of river.
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