With that failure and the final departure of the Legions, Regnum fell on evil days.  Its position as the key to those harbours which had given it its importance now exposed it to the first raids of the pirates.  These barbarians, according to legend, were Ella and his three sons, one of whom, Cissa, is said to have given Chichester her name—­Cissa’s camp, Cissa’s Ceaster.  Of Chichester’s story during the Dark Ages we know as little as we know of most of the cities of England, but that it was destroyed utterly, as has been asserted, common sense refuses to allow us to believe.  It certainly continued to exist, in barbarous fashion perhaps, but still to live, till with the conversion of the English it began to take on a new life, and with the Conquest was finally established as the seat of the Bishop.

The apostle of the South Saxons, St Wilfrid, wrecked upon the flat and inhospitable shore of Selsey, was, as we know, their first bishop.  He established his See, however, not at Chichester, but at Selsey where it remained until the Conqueror began to reorganise England upon a Roman plan, when more than one See was removed from the village in which it had long been established to the neighbouring great town.  So it was with the Bishopric of Sussex, which in the first years of the Norman administration was removed from Selsey to Chichester.

Thus Chichester was restored in 1075 to the great position it had held in the time of the Romans.  Its lord was that Roger de Montgomery who received it from the Conqueror, together with more than eighty manors, and to him was due the castle which stood in the north-east quarter, and the rebuilding of the Roman walls, which continually renewed and rebuilt, still in some sort stand, upon Roman foundations, and mark the limits of the Roman town.

Of the South Saxon cathedral church at Selsey we know almost nothing.  It seems to have been established as a Benedictine house under an abbot who was also bishop, but later the monks were replaced by secular canons.  Then when in 1075 the See was removed from Selsey to Chichester the old church dedicated in honour of St Peter, which stood upon the site of the present cathedral, was used as the cathedral church, and the Benedictine nuns, to whom it then belonged were dispossessed in favour of the canons.  This, however, did not last long; by 1091 a new Norman church, the work of Bishop Ralph, whose great stone coffin stands in the Lady Chapel, had been built upon this site and dedicated in honour of the Blessed Trinity, the old church being commemorated in the nave, which still was used as the parochial church of St Peter Major.  This new building, however, was soon so badly damaged by fire that it was necessary to rebuild it—­this in 1114; but a like fate befell it in 1187, and again the church was restored, this time by Bishop Seffrid.  Then in the thirteenth century came Bishop Richard.  He was consecrated in 1245, and ruled the diocese for eight years.  This man was a saint, and in 1261 he was canonised.  Thus Chichester got a shrine of its own, which became exceedingly famous and attracted vast crowds of pilgrims, and thus indirectly brought so much money to the church that great works, such as the transformed Lady Chapel, and the many chapels which the Cathedral boasts, were able to be undertaken.