In subsequent years, beginning in the 1820s, Fort Richmond, Fort Hamilton, and Fort Lafayette at the Narrows of New York Harbor reduced the need for the Upper Harbor forts, and in time, the Army transferred most properties in Upper New York Bay to other federal agencies or sold them to the state of New York.
Fort Columbus, however, possessed 68 acres (280,000 m²), a sufficient land mass for a modest garrison at a reasonable proximity (1,000 yards (910 m)) to Manhattan, making it the most practical of the Second System forts for the Army to retain and continue to garrison.

Personnel stationed at Fort Columbus began to record meteorological observations in the 1820s.

As the closest major army post to the United States Military Academy at West Point, New York, Fort Columbus for many years served as a first posting or a major departure point for newly graduated cadets shipping to army posts along the Atlantic or Pacific coasts.
Many future generals in the Civil War were posted to or passed through Fort Columbus as young junior officers.
They included John G. Barnard, Horace Brooks, Abner Doubleday, Ulysses S. Grant, Robert E. Lee, Joseph E. Johnston, John Bell Hood, Theophilus H. Holmes, Thomas Jackson, Henry Wager Halleck, James B. McPherson and others.

In the 1830s, the protective value of Fort Columbus diminished with the advance of weapons technology, but other uses evolved for the army post.
The Army renovated the fortification beginning in 1833 with the construction of four barracks that remain to the present day, replacing wooden barracks.
The barracks were built as the fortification's importance in protecting New York was diminished by the construction of the new forts at The Narrows of New York Harbor.
The Greek Revival style barracks, unified by two-story Tuscan porticos first served as officers' and enlisted men's housing for the permanent garrison.
That same year the Ordnance Department established the New York Arsenal as a separate installation, adjacent to but not part of Fort Columbus, as a major depot taking delivery of contracted manufactured arms and weapons and distributing both contract and federally manufactured weapons to army posts across the nation.
In 1836, the South Battery became the Army School of Music Practice, training young boys to become company drummers and fife players and regimental musicians.

The army located its General Recruiting Service for infantry troops at Fort Columbus in November 1852, and many regiments in the army detailed officers to Fort Columbus on recruiting details.

Twice, in December 1860 and April 1861, the Army "secretly" dispatched troops and provisions from Fort Columbus to relieve the besieged garrison at Fort Sumter in Charleston, South Carolina.
 Outgoing President James Buchanan initiated the first effort, but a battery garrisoned by cadets from The Citadel, The Military College of South Carolina fired on the Army-chartered New York-based steamship Star of the West on January 9, 1861 as it entered Charleston Harbor.
The incident provoked a crisis, prompting other southern states began to more seriously consider secession from the Union.
 The second effort, with new Army recruits departing from Fort Columbus on April 9, 1861, also failed when it prompted South Carolina forces to fire on Fort Sumter early in the morning of April 12, 1861, resulting in the start of the Civil War.

In the early years of the Civil War, the north barracks were used to hold Confederate officers taken as prisoners of war pending transfer to other Union prisons such as Camp Johnson in Ohio, Fort Delaware or Fort Warren in Boston Harbor.
Fort Columbus and Castle Williams also served as a temporary prisoner of war camp and confinement hospital for Confederate prisoners during the war.
 Major General William H. C. Whiting (CSA) died of dysentery in February 1865 in the post hospital shortly after his surrender at the Battle of Fort Fisher, North Carolina.
He was the highest ranking Confederate officer to die as a prisoner of war.

Late in war and the immediate years after it, the armament of the
In subsequent years, beginning in the 1820s, Fort Richmond, Fort Hamilton, and Fort Lafayette at the Narrows of New York Harbor reduced the need for the Upper Harbor forts, and in time, the Army transferred most properties in Upper New York Bay to other federal agencies or sold them to the state of New York. Fort Columbus, however, possessed 68 acres (280,000 m²), a sufficient land mass for a modest garrison at a reasonable proximity (1,000 yards (910 m)) to Manhattan, making it the most practical of the Second System forts for the Army to retain and continue to garrison.
Personnel stationed at Fort Columbus began to record meteorological observations in the 1820s.
As the closest major army post to the United States Military Academy at West Point, New York, Fort Columbus for many years served as a first posting or a major departure point for newly graduated cadets shipping to army posts along the Atlantic or Pacific coasts. Many future generals in the Civil War were posted to or passed through Fort Columbus as young junior officers. They included John G. Barnard, Horace Brooks, Abner Doubleday, Ulysses S. Grant, Robert E. Lee, Joseph E. Johnston, John Bell Hood, Theophilus H. Holmes, Thomas Jackson, Henry Wager Halleck, James B. McPherson and others.
In the 1830s, the protective value of Fort Columbus diminished with the advance of weapons technology, but other uses evolved for the army post. The Army renovated the fortification beginning in 1833 with the construction of four barracks that remain to the present day, replacing wooden barracks. The barracks were built as the fortification's importance in protecting New York was diminished by the construction of the new forts at The Narrows of New York Harbor. The Greek Revival style barracks, unified by two-story Tuscan porticos first served as officers' and enlisted men's housing for the permanent garrison. That same year the Ordnance Department established the New York Arsenal as a separate installation, adjacent to but not part of Fort Columbus, as a major depot taking delivery of contracted manufactured arms and weapons and distributing both contract and federally manufactured weapons to army posts across the nation. In 1836, the South Battery became the Army School of Music Practice, training young boys to become company drummers and fife players and regimental musicians.
The army located its General Recruiting Service for infantry troops at Fort Columbus in November 1852, and many regiments in the army detailed officers to Fort Columbus on recruiting details.
Twice, in December 1860 and April 1861, the Army "secretly" dispatched troops and provisions from Fort Columbus to relieve the besieged garrison at Fort Sumter in Charleston, South Carolina.  Outgoing President James Buchanan initiated the first effort, but a battery garrisoned by cadets from The Citadel, The Military College of South Carolina fired on the Army-chartered New York-based steamship Star of the West on January 9, 1861 as it entered Charleston Harbor. The incident provoked a crisis, prompting other southern states began to more seriously consider secession from the Union.  The second effort, with new Army recruits departing from Fort Columbus on April 9, 1861, also failed when it prompted South Carolina forces to fire on Fort Sumter early in the morning of April 12, 1861, resulting in the start of the Civil War.
In the early years of the Civil War, the north barracks were used to hold Confederate officers taken as prisoners of war pending transfer to other Union prisons such as Camp Johnson in Ohio, Fort Delaware or Fort Warren in Boston Harbor. Fort Columbus and Castle Williams also served as a temporary prisoner of war camp and confinement hospital for Confederate prisoners during the war.  Major General William H. C. Whiting (CSA) died of dysentery in February 1865 in the post hospital shortly after his surrender at the Battle of Fort Fisher, North Carolina. He was the highest ranking Confederate officer to die as a prisoner of war.
Late in war and the immediate years after it, the armament of the
Fort Jay