In 897 King Alfred the Great with a fleet in the waters off the Solent, gained a complete victory over the Danes and later in the year captured 20 of their ships in the Channel. From that far-off day, Portsmouth with Gosport has been the chief home of the Navy.

Although no Charter has been found of earlier date than 1194, there is reason to believe that one was granted by King Henry the First in 1106 under the title of "Approved Men of Portsmouth", and that it was surrendered to King Richard the First in 1194 for a new Charter – at a price, for he was much in need of money at the time.

References to Portsmouth occur in the early 12th century but they almost certainly allude to the anchorage at the top of the harbour at the mouth of the estuary of the Wallington River. Portchester Castle and the village of Portchester stood nearby on the northern edge of this area. It is probably this site which is referred to in the Anglo-Saxon Chronicle which states that "in 501 A.D. Port and his two sons Bieda and Maegla came to Britain with two ships in the place called Portesmutha and killed a young British man, a very noble man."

Portsmouth was in fact founded by a wealthy Norman landowner and merchant, called Jean de Gisors, in approximately 1180, some fourteen years or so before the granting of the first charter. The facts themselves are recorded in the Southwick Cartularies which are the most important single source of information on Portsmouth, for the town`s own early records do not survive, destroyed it is believed in French raids on the town in the 14th Century.