The main defenses at Fort McHenry were located outside of the star fort itself. Under the direction of Captain Samuel Babcock, U.S. Army Engineers, civilian laborers, along with members of the First Marine Artillery of the Union, worked throughout the summer of 1813 on improving the Upper and Lower Water Batteries and mounting 18- and 36-pounder naval guns.
Upper Water Battery:
About 150’ up the hill from the southeast edge of the Parade Ground was the Upper Water Battery, also known as the “Old Battery.” This was a J-shaped earthwork originally built in 1776 as part of the works at Fort Whetstone, and abandoned in 1780. In 1794 the works were reconstructed and occupied by Captain Staats Morris’ Company of Artillerists and Engineers who were still here during the Quasi-war with France from 1798 to 1800. In 1813 the works were again improved under the direction of Captain Samuel Babcock, U.S. Army Engineers. The battery initially mounted six guns of 18- and 36-pounder size, with at least three more added prior to the battle in 1814.
A brick Hot Shot Furnace was located within the upper water battery centered in the rounded end of the work. Hot shot furnaces were used by the defenders to superheat solid shot before firing in order to set fire to the enemy’s ships.
Magazines were used to hold and protect ammunition, particularly powder and slow match. A 10’ x 20’ brick magazine was located to the rear and just to the left center of the battery. A second, larger (20’ x 20’) magazine was built next to the first, but it is unclear if this was before or after the battle.
Lower Water Battery:
The Lower Water Battery (Northeast Section) also dated from 1776. As with the Upper Battery this work was reconstructed between 1794 and 1798, then neglected until 1813. In the summer of that year, the parapet was rebuilt and extended around the south point of the fort in order to cover the Middle Branch of the Patapsco River. While the parapet was continuous, the guns were mounted in three sections. A brick revetment was built along the interior of the northeastern section, and the central section.
The Northeastern Section was located just below the Upper Water Battery This section was shaped in a zig-zag fashion. It had a wooden platform and mounted eleven 36-pounder guns.
A brick Hot Shot Furnace was located just behind the parapet at the base of the Upper Water Battery. A second Hot Shot Furnace was located half-way between the northeast section and the center section.
A straight section was located south of, and a little to the east of bastion number 4 of the star fort. It had a wooden platform and mounted a dozen 18 and 36-pounder guns.
A curved section of parapet was located south of and a little to the west of bastion number 4 of the star fort. This section was the smallest battery. It had two small platforms and mounted six 18-pounder guns.
September 13, 1814: On Tuesday morning, about sunrise, the British commenced their attack on Fort McHenry from "five bomb vessels at the distance of about two miles.” Finding that their shells reached the fort, the British anchored and kept up "an incessant and well directed bombardment." Major Armistead immediately ordered his batteries to open and "keep up a brisk fire...but the shot and shells all fell considerably short of him." This left the garrison "exposed to a constant and tremendous shower of shells without the most remote possibility of doing him the slightest injury."
At about 3:00 p.m., three bomb-ships advanced on the entrance to the harbor. At the Lazaretto Battery, Lieutenant Frazier's men stood ready, as did Lieutenant Rudder's Flotillamen on the eight gunboats in the channel.
When the British ships reached what Armistead believed to be "good striking distance," he ordered "fire to be opened, which was obeyed with alacrity" with "a roar that shook the whole harbor..." and within half-an-hour the "intruders again sheltered themselves by withdrawing beyond our reach." The garrison "gave three cheers and again ceased firing." The British ships "continued throwing shells," at the forts and batteries.