The first permanent settlement of the VOC in Semarang was protected by an earthwork embankment with a palisade. In 1695, the High Government decided to build a pentagonal brick fort at Kali Semarang north of the Chinese and Javanese settlement. After the work was finished in 1708 the fort got a garrison of 130 man. The bastions were called Zeeland, Amsterdam, Utrecht, Raamsdonk en Bunschoten.
After the construction of the fort the headquarters of the VOC settlements on the north coast moved from Jepara to Semarang, which had a good connection with the court of Mataram in Kartasoera.
During the Chinese Mataram uprising (1740-1743) the forts of the VOC at Kartasoera, Rembang and Demak were captured. The rebels attacked Semarang, which was undefended except for the fort. In a hurry earthen embankments and trenches were made as a line of defense. Against all expectations the defenders held out against a greater number of Chinese and Javanese attackers. After five months the siege was lifted by reinforcement arriving by ship from Batavia and Makassar. It proofed to be a turning point in the war. In November 1743 susuhunan Pakoebewono II signed a peace treaty in which he had to cede the north coast of Java to the Company.
The siege was the reason for the construction of a circumvallation wall around the city. The existing fort was demolished in 1746 with the exception of two bastions which became a part of the new brick wall. Semarang had a city plan of 600 x 400 meter with a bulge in the northwest corner, on the site of the demolished fort. The Chinese settlement, which was demolished to get a free field of fire, was rebuilt on the west bank of Kali Semarang.
After 1785 plans were developed to defend Semarang against an invasion of a European enemy. Surveyor Carl Friederich Reimer made designs of a modern circumvallation with a citadel and coastal batteries, but these were never built.
In 1824 the 18th century fortifications of Semarang were demolished and the moat filled.
Today there are no visible remains left of the fortifications of the VOC. Between 2000 and 2010 archaeologist excavated parts of the city wall and the fort.
