Isengard was a stronghold guarding the Gap of Rohan at the southern end of the Misty Mountains. The impregnable Tower of Orthanc stood within the walls of Isengard. Isengard was originally an outpost of Gondor, but in the later part of the Third Age it was home to the Wizard Saruman. During the War of the Ring, Saruman was defeated and the walls of Isengard were torn down by the Ents, and the Tower of Orthanc was reclaimed by Gondor.
Isengard was located in the deep valley of Nan Curunir, the Wizard's Vale, at the roots of Methedras, the last peak of the Misty Mountains. The Wizard's Vale opened to the south onto the Gap of Rohan, between the Misty Mountains and the White Mountains. The land of Rohan was on the eastern side of the Gap, and the forest of Fangorn lay to the northeast. West of the Gap was the region called Dunland.
The River Isen flowed through the Wizard's Vale. A paved road ran along the western bank of the river and then curved toward Isengard, which was about 16 miles into the valley on the western side.
The great circular wall of the Ring of Isengard came out of the arm of the mountain itself and was made of hard, black stone. The wall was in part a natural formation, but had been smoothed and shaped by the Men of Gondor. The diameter of the Ring was one mile across.
There was a single entrance on the south side of the Ring of Isengard. It was an arched tunnel bored through the rock wall, with great gates at either end. The gates were made of iron and had hinges of steel with posts driven into the sides of the tunnel. The gates swung easily and noiselessly on their hinges when opened, when closed, they were locked with bars.
Inside the tunnel on the left side there was a staircase leading to a guardroom. The guardroom was a large, dark, stone chamber with a fireplace and windows looking out into the tunnel. Beyond the guardroom was a store-room filled with provisions. Another staircase led from the store-room to the top of the wall over the gates.
Around the inner side of the Ring of Isengard, there were numerous other rooms and halls carved into the great wall. During Saruman's time, thousands of workers, slaves, and soldiers were quartered there, and wolves were kept in dens beneath the walls.
Within the Ring of Isengard was a large circular plain. The ground dipped slightly to form a shallow bowl, at the center of which stood the Tower of Orthanc. Orthanc was made of hard, gleaming black stone. The Tower was man-made but appeared like a great spur of rock thrusting out of the plain.
The Tower was composed of four, many-sided columns of rock joined together that rose to a height of 500 feet and then forked into four sharp pinnacles. Between the pinnacles was a small roof of polished stone carved with astronomical signs where a person could stand and watch the stars. This platform could be reached by a single staircase of many thousand steps inside the Tower.
The only door into Orthanc was on the eastern side, in the angle of two of the stone columns. The Keys of Orthanc were used to lock this door. A flight of 27 stone steps led up to the door. Above the door was a balcony with an iron railing, and a shuttered window opened onto the balcony. There were many more tall windows around the Tower of Orthanc, even in the four pinnacles.
In the early days of Isengard, there were gardens and groves of trees on the plain around Orthanc. Tree-lined paths led through the gardens and to the Tower. Streams came down from the mountainside onto the plain and converged to form a small lake.
In Saruman's time, the gardens were destroyed and the trees were cut down. The paths were paved and lined with pillars linked by chains. Deep shafts were dug into the plain leading to an underground network of treasuries, store-rooms, armories, and smithies where hammers pounded and wheels turned. Forges and furnaces worked day and night, sending smoke up through the shafts onto the plain.
After the War of the Ring, the plain was once again filled with gardens and orchards by the Ents, who called it the Treegarth of Orthanc. The Ring of Isengard was completely torn down, and in place of the gates there were two tall trees on either side of the main road. Orthanc was untouched, but now stood at the center of a reflecting pool of water.
In the early days of Gondor at the end of the Second Age, the Men of Gondor built the Tower of Orthanc of unbreakable stone, and they smoothed and shaped the walls of the Ring of Isengard from the living rock of the mountain. The stronghold was established to guard the Gap between the Misty Mountains and the White Mountains, which was a vulnerable point in Gondor's western defenses. Isengard guarded the northern side of the Gap, while the stronghold of Aglarond - later called Helm's Deep - guarded the southern side of the Gap.
For a time, Isengard was inhabited by lords of Gondor who were the wardens of the western borders. Men of learning also lived in Isengard and studied the stars from the pinnacle of Orthanc. The palantir called the Orthanc-stone was kept in the Tower and was used to communicate with other parts of the realm. Orthanc was considered one of the three Towers of Gondor, along with Minas Anor and Minas Ithil.
Over time, however, the watch on the western border of Gondor decreased. The main threat came from enemies in the East, and thus the bulk of Gondor's defenses were focused in that direction. The population of Calenardhon - the western region of Gondor near Isengard - diminished during the Great Plague of 1636, and more of the inhabitants moved eastward during the Watchful Peace of 2063-2460 to man the forts along the Anduin.
Isengard was left in the care of local hereditary chieftains. The chieftains were Men of Gondor, but their subjects who dwelled in and around Isengard had become mixed with the Dunlendings who had begun to migrate from west of the Misty Mountains.
In 2510, Calenardhon was overrun by Easterlings and Orcs. Isengard was besieged during the invasion. The enemy forces were defeated at the Battle of the Field of Celebrant by the Eorlingas, who had been led from the North by Eorl the Young. Cirion, the Steward of Gondor, gave the Eorlingas the land of Calenardhon as a reward, and it became known as Rohan.
Isengard remained a stronghold of Gondor, though it was now separated from the rest of Gondor by the land of Rohan. The chieftain and his people continued to dwell in the Ring of Isengard, but the Tower of Orthanc was locked and the Keys were taken to Minas Tirith. Contact with Minas Tirith decreased and finally ceased, and Isengard became an isolated outpost.
During the reigns of King Brego and King Aldor of Rohan, the Dunlendings were driven out of Rohan. The Dunlendings grew to hate the Rohirrim and they became an enemy of Rohan.
The line of Gondorian chieftains at Isengard ended, and command of the stronghold was taken over by a local family who were of mixed blood and were friendly with the Dunlendings. After the death of King Aldor, the Dunlendings once again began to migrate through the Gap of Rohan. They were helped by the inhabitants of Isengard and settled in the mountains nearby.
In 2710, the Dunlendings took over Isengard. Most of the inhabitants of Isengard welcomed them, and those who remained loyal to Gondor were killed. The Dunlendings then began to raid the herds of horses in the Westfold, prompting King Deor of Rohan to lead a force to stop them. Deor defeated the raiders but was surprised to find that Isengard had been captured. The Rohirrim were unable to retake the stronghold. Deor sent a message to Egalmoth, the Steward of Gondor, but he was unable to send help. Isengard remained in the possession of the Dunlendings until the Long Winter of 2758-59, when they were starved out and surrendered to King Frealaf of Rohan.
In 2759, Saruman the White - the Chief of the Order of Wizards and head of the White Council - offered to take up residence in Isengard. Since Gondor was no longer able to maintain an adequate garrison at Isengard, the Steward Beren agreed and gave Saruman the Keys of Orthanc. The Rohirrim were also happy to have a powerful Wizard guarding a strategic point on their border with Dunland. For his part, Saruman was attracted by the strength of Isengard's position and defenses, and he also wanted access to the palantir in the Tower of Orthanc.
Saruman was entrusted with Isengard as a warden of the Steward of Gondor, but the Wizard had plans to expand his power. In 2953, he claimed Isengard as his own and isolated himself within its walls. Saruman began to fortify the stronghold and to assemble an army consisting of Orcs, Men of Dunland, and some creatures that appeared to be a mixture of both.
Saruman's army was housed in chambers built into the inner wall of the Ring of Isengard, and he kept wolves in dens beneath the wall. He destroyed the beautiful gardens and orchards of Isengard, and he built an underground network of workshops and forges to supply his army with weapons of war. Saruman intended to use his position of strength in Isengard in order to conquer Rohan as a first step toward his goal of ruling the world of Men.
On July 10, 3018, Gandalf the Grey came to Isengard, lured by a message from Saruman. When Gandalf refused to join forces with Saruman, Saruman imprisoned Gandalf atop the pinnacle of Orthanc. Gandalf was trapped on the small roof exposed to the elements until he was rescued by Gwaihir the Windlord on September 18.
In 3019, Saruman launched his attack on Rohan. At the First Battle of the Fords of Isen on February 25, a force from Isengard killed Theodred, the son of King Theoden. On March 2, Saruman began to unleash his full force from Isengard. During the day and early evening, a company of Saruman's best fighters to broke the defenses of the Rohirrim at the Second Battle of the Fords of Isen. Then at midnight, an army of over 10,000 Orcs, wolves, and Men came forth from Isengard, taking over an hour to pass through the gates. The army marched to Helm's Deep to besiege the Rohirrim, but they were ultimately defeated.
As soon as the gates were closed behind the departing army, Treebeard and the Ents attacked Isengard. The Ents ripped the gates from their hinges and began to tear down the great wall encompassing the Ring of Isengard. Most of the southern wall was destroyed, leaving only the archway where the gates had hung and the adjacent guardroom. A great crack was made in the northern part of the wall as well.
Saruman locked himself inside Orthanc. The Ents could not get a grip on the smooth, hard surface of the Tower and they were unable damage it beyond a few scratches and chips. Saruman attacked the Ents with liquid fire and fumes from vents and shafts in the grounds of Isengard. The Ents responded by gathering the waters of the River Isen and diverting them through the gap in the northern wall so that the Ring of Isengard was flooded. Water poured down into the shafts and doused the fires of Saruman's furnaces and forges.
The Hobbits Merry Brandybuck and Pippin Took, who had accompanied the Ents, explored the grounds of Isengard. They discovered several store-rooms filled with provisions including barrels of Longbottom Leaf - a type of pipe-weed from the Shire, where Saruman had secret contacts.
On March 5, Gandalf and King Theoden arrived at Isengard to parley with Saruman. Saruman refused to give in, and Gandalf broke his staff and cast him from the Order of Wizards. As Gandalf and the others were leaving, Saruman's servant Grima threw the palantir down from Orthanc.
Saruman and Grima remained imprisoned in Orthanc under the guard of Treebeard and the Ents for the duration of the War of the Ring. The Ents formed a lake around Orthanc to prevent Saruman from escaping through a tunnel. They tore down the remainder of the Ring of Isengard and cleared away the rubble. The Ents then planted gardens and trees, and the grounds around the Tower were renamed the Treegarth of Orthanc.
Aragorn, King Elessar of the Reunited Kingdom of Gondor and Arnor came to Orthanc on August 22. Aragorn gave the Ents permission to inhabit the valley and asked them to keep watch over Orthanc. Treebeard gave the Keys of Orthanc to Aragorn, and the Tower of Orthanc was once again under the authority of the King. Aragorn ordered the restoration of Orthanc, and many treasures stolen by Saruman were discovered including the Elendilmir. The Orthanc-stone was returned to its place in the Tower, and Aragorn came to Orthanc from time to time and used the palantir to survey his realm.