Question: When was the fort commanded by George Armistead during the Battle of Baltimore first built?

full_context: Document 1: Fort McHenry: Fort McHenry, in Baltimore, Maryland, is a historical American coastal pentagonal bastion fort best known for its role in the War of 1812, when it successfully defended Baltimore Harbor from an attack by the British navy from the Chesapeake Bay September 13–14, 1814. It was first built in 1798 and was used continuously by U.S. armed forces through World War I and by the Coast Guard in World War II. It was designated a national park in 1925, and in 1939 was redesignated a "National Monument and Historic Shrine".
Document 2: The Star-Spangled Banner: "The Star-Spangled Banner" is the national anthem of the United States of America. The lyrics come from "Defence of Fort M'Henry", a poem written on September 14, 1814, by the 35-year-old lawyer and amateur poet Francis Scott Key after witnessing the bombardment of Fort McHenry by British ships of the Royal Navy in Baltimore Harbor during the Battle of Baltimore in the War of 1812. Key was inspired by the large American flag, the Star-Spangled Banner, flying triumphantly above the fort during the American victory.
Document 3: George Meade: George Gordon Meade (December 31, 1815 – November 6, 1872) was a career United States Army officer and civil engineer involved in the coastal construction of several lighthouses. He fought with distinction in the Second Seminole War and the Mexican–American War. During the American Civil War he served as a Union general, rising from command of a brigade to command of the Army of the Potomac. He is best known for defeating Confederate General Robert E. Lee at the Battle of Gettysburg in 1863.
Document 4: North Point State Battlefield: North Point State Battlefield is a publicly owned historic preserve in Dundalk, Baltimore County, Maryland, that commemorates a portion of the site where the Battle of North Point was fought during the War of 1812. On September 12, 1814, Brigadier General John Stricker commanded forces of the Maryland Militia from within the park's borders. Stricker's men fought the invading British forces from behind a fenceline along the monument's eastern edge.
Document 5: Battle Monument: The Battle Monument, located in Battle Monument Square on North Calvert Street between East Fayette and East Lexington Streets in Baltimore, Maryland, commemorates the Battle of Baltimore with the British fleet of the Royal Navy's bombardment of Fort McHenry, the Battle of North Point, southeast of the city in Baltimore County on the Patapsco Neck peninsula, and the stand-off on the eastern siege fortifications along Loudenschlager and Potter's Hills, later called Hampstead Hill, in what is now Patterson Park since 1827, east of town. It honors those who died during the month of September 1814 during the War of 1812. The monument lies in the middle of the street and is between the two Baltimore City Circuit Courthouses that are located on the opposite sides of North Calvert Street. It was sponsored by the City and the "Committee of Vigilance and Safety" led by Mayor Edward Johnson and military commanders: Brig. Gen. John Stricker, Maj. Gen. Samuel Smith and Lt. Col. George Armistead (of Ft. McHenry).
Document 6: George Armistead: George Armistead (April 10, 1780 – April 25, 1818) was an American military officer who served as the commander of Fort McHenry during the Battle of Baltimore in the War of 1812.
Document 7: James Armistead Lafayette: James Armistead Lafayette (December 10, 1760 – August 9, 1830) was an enslaved African American who served the Continental Army during the American Revolutionary War under the Marquis de Lafayette. As a double agent, he was responsible for reporting the activities of Benedict Arnold – after he had defected to the British – and Lord Cornwallis during the run-up to the Battle of Yorktown. He fed them false information while disclosing very accurate and detailed accounts to the Americans.
Document 8: Mary Young Pickersgill: Mary Pickersgill (born Mary Young; February 12, 1776 – October 4, 1857), was the maker of the Star Spangled Banner Flag hoisted over Fort McHenry during the Battle of Baltimore in the War of 1812. The daughter of another noted flag maker, Rebecca Young, Pickersgill learned her craft from her mother, and, in 1813, was commissioned by Major George Armistead to make a flag for Baltimore's Fort McHenry that was so large that the British would have no difficulty seeing it from a great distance. The flag was installed in August 1813, and, a year later, during the Battle of Baltimore, Francis Scott Key could see the flag while negotiating a prisoner exchange aboard a British vessel, and was inspired to pen the words that became the United States National Anthem.
Document 9: Armistead Monument: The Armistead Monument is a bronze statue of Col. George Armistead, by Edward Berge.
Document 10: Fort Warren (Massachusetts): Fort Warren is a historic fort on the 28 acre Georges Island at the entrance to Boston Harbor. The fort is pentagonal star fort, made with stone and granite, and was constructed from 1833–1861, completed shortly after the beginning of the American Civil War. Fort Warren defended the harbor in Boston, Massachusetts, from 1861 through the end of World War II, and during the Civil War served as a prison for Confederate officers and government officials. The fort remained active through the Spanish–American War and World War I, and was re-activated during World War II. It was permanently decommissioned in 1947, and is now a tourist site. It was designated a National Historic Landmark in 1970 as a masterpiece of coastal engineering of the pre-Civil War period, and for its role in the Civil War. It was named for Revolutionary war hero Dr. Joseph Warren, who sent Paul Revere on his famous ride, and was later killed at the Battle of Bunker Hill. The name was transferred from the first Fort Warren in 1833, which was renamed Fort Winthrop.
Document 11: Fort Morgan (Alabama): Fort Morgan is a historic masonry Pentagonal bastion fort at the mouth of Mobile Bay, Alabama, United States. Named for Revolutionary War hero Daniel Morgan, it was built on the site of the earlier Fort Bowyer, an earthen and stockade type fortification involved in the final land battles of the War of 1812. Construction was completed in 1834 and it received its first garrison in March of the same year.
Document 12: Battle of Baltimore: The Battle of Baltimore was a sea/land battle fought between British invaders and American defenders in the War of 1812. American forces repulsed sea and land invasions off the busy port city of Baltimore, Maryland, and killed the commander of the invading British forces. The British and Americans first met at North Point. Though the Americans retreated, the battle was a successful delaying action that inflicted heavy casualties on the British, halted their advance and allowed the defenders at Baltimore to properly prepare for an attack.
Document 13: USS Fort McHenry (LSD-43): USS "Fort McHenry" (LSD-43) is a "Whidbey Island"-class dock landing ship of the United States Navy. She was named for Fort McHenry, in Baltimore, Maryland, the 1814 defense of which inspired "The Star-Spangled Banner".
Document 14: Star-Spangled Banner (flag): The Star-Spangled Banner, or the Great Garrison Flag, was the garrison flag that flew over Fort McHenry in Baltimore Harbor during the naval portion of the Battle of Baltimore during the War of 1812. Seeing the flag during the battle inspired Francis Scott Key to write the poem "Defence of Fort M'Henry", which, retitled with the flag's name from the closing lines of the first stanza and set to the tune of "To Anacreon in Heaven" by John Stafford Smith, later became the national anthem of the United States.
Document 15: Baltimore National Heritage Area: Baltimore National Heritage Area is a federally designated National Heritage Area encompassing portions of Baltimore, Maryland, USA. The designated area includes the central portion of the city, waterfront, inner neighborhoods and portions of the city's park system. The district includes Fort McHenry and the Inner Harbor, as well as portions of the Charles Street, Falls Road, National Historic Seaport and Star Spangled Banner Maryland Scenic Byways. The Baltimore National Heritage Area was established on March 30, 2009 by the Omnibus Public Land Management Act of 2009 (Pub.L. 111–11 §7002). The designation recognizes the area's unique historic and cultural character, and is intended to stimulate economic development, tourism and historic preservation.
ground_truth: 1798