By the early 12th century, timber castles across England were increasingly replaced or reinforced with stone to improve their defensive capabilities. Around 1127, the construction of the massive stone keep at Rochester Castle began, likely also under the direction of Bishop Gundulf or his successors.

The stone keep, completed by about 1136, was one of the finest and largest Norman keeps in England. It measured approximately 35 meters (115 feet) square and stood 30 meters (100 feet) tall, with walls up to 4.3 meters (14 feet) thick. This massive structure was built primarily from Kentish ragstone, quarried nearby, and featured typical Norman architectural elements such as rounded arches and narrow windows suitable for defense.

The keep’s design was both symbolic and practical: it signified Norman authority and power while providing a near-impenetrable refuge for the castle’s defenders in times of siege.

Rochester Castle in the Anarchy (1135–1154)

The period known as The Anarchy was a civil war in England triggered by a succession crisis after the death of Henry I in 1135. Two rivals, King Stephen and Empress Matilda (Henry’s daughter), contested the throne. This led to widespread instability, with nobles taking sides and fortifying castles to protect their holdings.

Rochester Castle played a pivotal role in this conflict. Initially, it was held by Bishop Gundulf’s successors, but by 1137 it was in the hands of King Stephen’s supporters. However, in 1137, Stephen himself besieged Rochester Castle, held by rebel forces loyal to Empress Matilda.

The siege lasted several months, with Stephen’s forces struggling to breach the castle’s formidable defenses. The defenders were able to hold out, but eventually, a relief force loyal to Stephen arrived, and the castle changed hands multiple times during the course of the war.

This period solidified Rochester Castle’s reputation as a fortress that could withstand prolonged attacks, and its strategic importance was unquestioned. shutdown123