In the 5th century, the Romans were under attack from Saxon pirates on the south coast which lead to the development of the curtain wall and bastions to better defend the castle and give safe anchorage for ships.
The evidence which is still visible today is the curtain wall and the bastions.
From 500ad – 1066, the Saxons controlled Portchester castle adding to it a hall and a tower in the south-west quarter of the fort. The evidence still visible today is the hall and tower.
William Maudit was thought to have created the inner bailey, the inner arch of the water gate and protection around the buildings. The evidence still visible today are the inner bailey, the ditches around it and the water gate arch.
Richard II: Richard II built a palace in the castle grounds in 1396-99. this was built to provide a comfortable living space for himself and his guests. The evidence still visible today is the walls and the foundations of the palace.
In 1415, Henry V prepared at Portchester for the campaign against the French at Agincourt. This is when the castle fell into disrepair because the Tudor ships were to big to fit inside the harbour.
Prisoners of war:
In 1760, 3200 prisoners were held in Portchester castle on many floors of the keep including officers and peasants. Although, higher ranking officers were treated better than others. The evidence still visible today is the graffiti on the walls of the keep dating back to the 1800’s, and the hooks on the wooden beams which were used to hold hammocks for the prisoners to sleep in.
Since the end of the sites use as a defence purpose and to hold the royal family. the English heritage has looked after the castle and its grounds to preserve what is left of it for future generations. It is now open as a tourist attraction to the general public.
I believe from what I have researched and found out, that Portchester castle started to fall into disrepair around the Tudor time. This was because the Tudor ships were to large to fit inside the harbour surrounding Portchester.