Portus Adurni facts for kids
Portus Adurni was a strong Roman fort located at the top of Portsmouth Harbour in Britannia, which was a Roman province. It was part of the Saxon Shore defense system. This fort is the best-preserved Roman fort found north of the Alps mountains! Only about one-eighth of the fort has been dug up by archaeologists.
Later, this Roman fort was changed into a medieval castle. Today, it is known as Portchester Castle.
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What Was Portus Adurni?
The name Portus Adurni is only found in an old list from the 5th century called the Notitia Dignitatum. This list names all the forts along the Saxon Shore. Most people agree that Portus Adurni is the same place as Portchester.
Some people thought it might be another Roman fort called Walton Castle, Suffolk, but that fort has now been washed away by the sea. The name Portus Adurni might also be connected to Ardaoneon, another old name. Both names probably come from a British word meaning "height." This makes sense for Portchester, which is near Portsdown Hill.
The Roman Fort's Design
The fort was built in the 200s AD. It was part of the Saxon Shore forts, which were built to protect the southern coast of Roman Britain. They likely defended against Saxon raiders who attacked from the sea.
Portus Adurni is in a great spot at the head of Portsmouth Harbour. The fort is square-shaped and covers about 9 acres (36,000 square meters). Its outer walls are very impressive. They are 20 feet (6 meters) high and 10 feet (3 meters) thick. Each side of the square fort is about 210 yards (200 meters) long. The walls were built using flint stones held together with limestone slabs.
Square forts became popular in the 200s AD because they were easy to defend. Portus Adurni has many towers along its walls. It also has special towers that stick out at the corners. Historians think this strong defense shows how serious the Saxon raids were. It might also show the need for defense during the Carausian Revolt (which you can read about below).
The gates of Portus Adurni are also very interesting. They are built inwards, creating a trap for enemies. If attackers entered the gate, they would be surrounded by walls on three sides. This clever defense method was used for a long time, from the time of Emperor Augustus until the Roman Empire fell.
It's rare for such an old building, but most of the fort's walls and towers are still standing. Only four of its towers are missing. Over time, some stones from the walls were used for new buildings. But from the outside, the walls still look much like they did when they were first built. The walls were constructed in sections by different groups of workers. This is why you can see different textures as you walk along the outside.
History of the Fort
The Saxon Shore forts, including Portus Adurni, were built in the mid to late 200s AD. This was a time when there was a lot of trouble in northern Gaul and the Rhineland. Eventually, the Romans had to leave those areas. The forts were meant to keep control of the region. They also watched over ships and trade, and defended against raids from across the English Channel.
These forts became important strongholds for a rebel leader named Carausius. In 285 AD, Carausius was given the job of stopping Saxon pirates in the English Channel. But he was accused of keeping the pirates' stolen goods for himself. So, he went to Britain and declared himself Emperor.
His revolt lasted for almost 10 years. Other Roman generals tried to defeat him but failed. Finally, in 293 AD, Carausius was murdered by Allectus, one of his helpers. Britain was taken back by the Roman Empire in 296 AD.
We don't know for sure who built Portus Adurni. Some Saxon Shore forts were built by earlier commanders or emperors. But some were built by Carausius during his revolt. Evidence suggests that Portus Adurni was built when Carausius was in charge. Many of the old coins found at the site were made by Carausius when he was the rebel emperor.
Anglo-Saxon Residence
Even after the Roman Army left Britain, Portus Adurni was still a great place for a fortress. Its location and strong walls made it very useful. The fort became a fancy home for important Anglo-Saxon leaders. It had a large hall and a tower. Later, the Roman gateways were rebuilt too.
Portchester is listed as one of thirty-three fortified towns called burhs. These towns were built to protect people. This list is thought to be from the time of Edward the Elder, who was king from 899 to 924 AD.
Later Life of the Fort
The strong walls of the Roman fort became the outer walls of a Norman castle. Later, it was even a medieval palace. During the Napoleonic Wars, it was used as a jail.
The fort is in amazing condition because it was used for almost 1,600 years! Even though it was sometimes left empty or not taken care of, people kept coming back to it. Today, the site is owned by the Southwick Estate. But it is managed by English Heritage, and you can visit it all year round.
See also
In Spanish: Portus Adurni para niños
