According to a nearby information board:

The long foundation to the left (see picture above) was a barracks for enlisted men. The short foundation on the right (picture below) housed the fort’s senior officers and served as a commissary for storing food provisions. Items stored here were controlled and carefully guarded. Archaeology suggests that only the northern half of the cellar had a fireplace and may have been where the officers’ servants lived.

Construction was virtually constant during the 18 months Fort Montgomery was occupied. The Enlisted Men’s Barracks was one of the first two buildings erected in the fort. It was followed by other buildings, gun platforms, earthworks, and the construction of Fort Clinton across the creek.

There’s not much to see here nowadays, but this was once the site of the North Redbout.

According to a nearby information board:

Brigadier General George Clinton, the Governor of New York State, commanded Fort Montgomery during the battle of October 6, 1777. Aware the British were approaching, he ordered some of his men to take a 3-pounder cannon down the western road leading to the fort to slow the enemy. The Americans temporarily stopped the 900 advancing British and Loyalist soldiers under the command of Lieutenant Colonel Mungo Campbell, but were eventually forced to abandon their gun and return to the fort.

Governor Clinton ordered his undermanned garrison into the fort’s three redoubts, or strong points. British skirmishers approached keeping up a constant fire. After being driven back, the British sent a flag to the fort seeking the Americans’ surrender. When the Americans refused, the British resumed the battle and after several attacks, finally drove the Americans from the redoubts.

As Governor Clinton was rallying his men to continue the fight, a roaring cheer went up from Fort Clinton, proclaiming its capture by the British. Governor Clinton and more than half of the Americans escaped from Fort Montgomery, taking advantage of the battle’s haze and the growing darkness. By nightfall, the British controlled both forts and the Battle of Fort Montgomery was over. All subsequent testimonies by the officers agreed that the soldiers had fought bravely, but that there had not been enough men to defend the forts adequately.

…

The term redoubt at Fort Montgomery means a strong point in the fort’s walls. There were three redoubts at Fort Montgomery, including the North Redoubt, which you see here. Two of the redoubt’s walls projected out from the fort so that enemies approaching the walls of the fort would be exposed to cannon and musket fire from the redoubt. About 15 feet outside the redoubt was a two-foot deep ditch, which would have slowed an approaching enemy.

The lower portions of the redoubt’s walls were formed of earth faced with stones. Assuming the redoubt was built like other sections of the fort, the upper part of the redoubt’s walls were faced with bundles of saplings, called fascines. Around the inside of the redoubt’s walls there was a banquette, or firing step, that soldiers could stand on to fire over the wall. The redoubt probably contained a few 6- or 12-pounder cannons. Archaeologists found evidence of charred wood in the “point” of the redoubt, which was probably the remains of a cannon platform. The presence of pothooks, a fork, bottle glass, ceramics, teapots, and bone scraps suggests that soldiers gathered here to eat and socialize.

According to the Revolutionary War 101 site:

Lt. Col. Mungo Campbell and several British regulars approach the fort with a flag of truce indicating that they wish to avoid `further effusion of blood.’ Clinton sends Lt. Col. William S. Livingston to meet the enemy. The British officer requests that the patriots surrender. They are promised that no harm would come to them. Livingston, in turn, invites Campbell to surrender and promises him and his men good treatment. Fuming at this audacity, the British resume the fight. British ships working against an ebb tide attack the forts and American vessels. A steady volley ensues with each side receiving a share of the bombardment. British officers Campbell and Vaughan close in on all sides of the twin forts. Leading his men into battle, Campbell is killed in a violent attack on the North Redoubt of Fort Montgomery. Vaughan’s horse is shot from under him as he rides into battle at Fort Clinton.

After a fierce battle lasting until dark, the British pushed the courageous Americans from the forts at the points of their bayonets. The defenders are overpowered by sheer numbers and the British gain possession of Forts Montgomery and Clinton. American casualties numbered about 350 killed, wounded and captured, while the British paid a price of at least 190 killed and wounded. Those who were not killed or did not escape are shipped to the infamous Sugar House Prisons in New York City and then onto British “hell ships” (prison ships) in the harbor. A “return,” or report of prisoners, is sent to communities in the Highlands to inform families of their loved ones’ capture. It is up to the families to send provisions lest the prisoners starve. Countless patriots perish on the prison ships.

According to a nearby information board:

You are looking at the foundation of a barracks built in the summer of 1776. This was probably a two-story building with a cellar under the northern half. Artifacts recovered from the site tell us a lot about the soldiers who lived here. In the 18th century, shoe buckles, brass and silver buttons, cuff links, glass tableware, tea services and flatware were symbols of elevated social status. The large quantity of these items recovered from all the barracks excavated at Fort Montgomery challenges traditional assumptions that these soldiers were poor and unsophisticated.

An abundance of cattle, pig, sheep, chicken, duck, pigeon, and fish bones was found in a large trash dump just outside the building’s west wall, indicating that the soldiers were generally well-supplied with meat. The animals were probably butchered on site and the meat cooked in soups and stews that were eaten from bowls using large pewter spoons. The scarcity of bones and other debris inside the barracks suggests that the soldiers regularly cleaned the building.

According to a nearby information board:

Fort Montgomery’s powder magazine provided secure, dry place in which to store the garrison’s gunpowder and ammunition. The magazine was located here because of the site’s good drainage and because of the protection afforded by the rock ridge between it and the river. The magazine was build early in the fort’s construction. By the middle of June 1776, its 8-foot thick walls were completed, and masons were ready to finish its arched brick vault. Once finished, the arch was covered with sandy soil and a roof was built over top to finish the magazine.

Some of Fort Montgomery’s powder was produced a Henry Wisner’s powder mill 20 miles away in Goshen, New York. The loose powder was stored in the magazine in 100-pound barrels until it was used to make cartridges for muskets and cannons. This magazine served both Forts Montgomery and Clinton. During the battle, however, the British cut off communications between the two forts by capturing the pontoon bridge. When the British overran Fort Clinton, its garrison was running out of ammunition.

According to a nearby information board:

When excavation of the Guard House was completed in 1969, the site was reburied to protect the feature. Therefore, little is visible today. The Guard House was divided into two rooms that reflected its dual uses. The southeastern room was where soldiers on guard duty were stationed. The northwestern room was used to house prisoners. It had a floor of mortar poured directly on the bedrock, presumably to keep prisoners from escaping through the floor. There is no evidence of bars or any other means of physically confining prisoners, so it is likely that the only access to the prisoners’ room was through the other room where the guard was stationed.

A number of courts-martial were held at Fort Montgomery. Soldiers were usually confined in the Guard House until their appearance before the court. Many soldiers brought before the court were charge with drunken behavior or failing to report for roll call. Abuse of officers, letting a prisoner escape, and a murder were among the more serious charges. Punishment ranged from small fines and public reprimands to demotions or public floggings.