Statistics for occurrence #1 of “Drewry's Bluff” in chapter 15 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.:
...e unfinished works placed them in as strong a condition as possible, and the outer line was started.
When the Federal army began its advance from Yorktown, there were only three guns in position on Drewry's Bluff , but, owing to the fear that the Union gunboats would ascend the river past the batteries further down, several ship's guns were also mounted to cover the obstructions in the channel.
On May 15th...
† 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.