The Normans built their first castle at Hastings soon after they arrived in 1066. They looked for sites that provided natural obstacles to an enemy, such as a steep hill or a large expanse of water. It was also be important to have good views of the surrounding countryside.
After his coronation in 1066, William the Conqueror claimed that all the land in England now belonged to him. William retained about a fifth of this land for his own use. The rest was distributed to those men who had helped him defeat Harold at the Battle of Hastings. The 170 tenants-in-chief (or barons) had to provide armed men on horseback for military service. The number of knights a baron had to provide depended on the amount of land he had been given.
The Norman conquerors realised that with only 10,000 soldiers in England, they would be at a disadvantage if the one and a half million Anglo-Saxons decided to rebel against them. To defend the territory they had conquered, the Normans began building castles all over England. Richard Fitz Gilbert, like the other Norman leaders, looked for sites that provided natural defences such as a steep hill or a large expanse of water. To protect his estates in Kent, Richard built a castle at Tonbridge, by the side of the River Medway.
The castle, built in the motte-and-bailey style, was made of wood. Local peasants were forced to dig a deep circular ditch. The displaced earth was then thrown into the centre to create a high mound called a 'motte'. By the time they finished, the motte was 18 metres (60 feet) high. Richard's labourers erected a wooden tower on top of the mound. The tower provided accommodation and a look-out point.
A courtyard, known as the bailey, was built next to the mound. The bailey was linked to the mound by a bridge. If an attacking force managed to get inside the bailey, the bridge could be pulled up to keep the invaders away from the people in the tower. The bailey was enclosed by a fence of wooden stakes called a palisade. The enclosed area would provide a site for houses and stables. Richard's labourers also built a bridge across the ditch that surrounded the castle. When filled with water, this ditch became known as a moat. The River Medway provided a constant supply of water for the moat at Tonbridge.