DescriptionCastle Comet is built upon a rock which stands in the sea a little less than half a mile from the east coast of Guernsey, opposite the town of St. Peter Port. Until the building of the present harbour and breakwater, this rock could only be reached on foot at low spring tides, that is for a few hours at each tide on three or four days in the month. The site offers many advantages. The castle walls could not be mined; they were not subject to battery until guns of sufficient weight could be mounted on ships or fired with sufficient range and accuracy from the coast of Guernsey; nor could the castle be besieged unless effective control of the surrounding seas were established. On the other hand, though a castle so situated might be very strong in itself, and while it might do much to protect shipping lying at anchor in the roadstead of St. Peter Port, it could do little to influence events in the island beyond. On two occasions, from 1340 until 1345 and from 1643 until 1651, Castle Cornet was held for some years against hostile forces established in Guernsey; while on several occasions, as in 1294, 1336 or 1372, the Island was overrun while the garrison of the Castle looked on helplessly.
Until the early years of the thirteenth century, while the Channel Islands were attached politically to the neighbouring coast of France, they had no strategic, political or economic importance, and there is very little evidence of any fortifications there. Indeed, in 1248, twenty-three Guemseymen said on oath, in a context that clearly refers to the time of King John’s accession and before: "At that time there were no castles in the Islands.” But when the king of France had annexed Normandy to his domain and established his suzerainty over Brittany, and yet left the Channel Islands in the possession of the king of England, their fortification became a matter of immediate necessity. The earliest reference we have to defensive works in Guernsey can be assigned to the year 1206 and although it is difficult to be sure until all the evidence both archaeological and documentary has been more closely studied, it would seem that the medieval Castle Cornet was built in a series of campaigns over a period of rather less than fifty years from that date, and that it retained its essential form, with additions and modifications in detail, until the sixteenth century.
The plan of the medieval castle was naturally moulded to the shape of the rock on which it was built. This rock is roughly triangular in plan with its apex pointing somewhat to the east of south. From the southern point it rose steeply to a height of about a hundred feet above the mean sea-level, and there was another summit of about the same height in the centre. The central summit was crowned by a great cylindrical tower, the donjon or keep; the southern summit carried a square tower. La Tour Carree. Between the two towers lay the southern or inner bailey; to the north lay another bailey with the main entrance to the castle, protected by a barbican, at the north-east extremity. The plan may thus be shortly described as one of two baileys, with a round keep standing astride the partition wall dividing them, a plan very similar to that of Pembroke Castle in South Wales. Nothing is at present known of any buildings or defences that may have stood outside these two baileys during the Middle Ages ; but it is unlikely that there were none, for what appears to have been the principal well of the castle lay outside the main walls on the eastern side and a considerable area was left unenclosed to the north where an enemy might have effected a lodgment.
The history of the medieval castle is not lacking in incident. Although there is no record of an attack upon it in 1294 or in 1336, when Guernsey was raided by the French, the garrison must have been standing to. But when Admiral Behuchet captured Guernsey and the lesser islands in 1338, he secured the Castle as well; and though English forces recovered the Islands in October 1340, following their naval victory at Sluys, the French were able to hold out in Castle Cornet until 1345; and they were in it again for a few months in 1356-7 When the Islands were raided and partly occupied between 1372 and 1377 and during the raids and invasions of the fifteenth and early sixteenth centuries, the Castle seems to have held. Its inability to shield Guernsey from attack, shown clearly in many of these incidents, is not likely to have diminished its importance in the eyes of the government which paid the expenses of its maintenance and the wages of its garrison ; for as long as it was politically and economically necessary for England to keep open the sea route from London and Southampton to Bordeaux and Bayonne, the roadstead of St. Peter Port was used by hundreds of ships annually, and it could have been used by none if Castle Comet were in enemy hands. On occasion, it seems, the Castle could do more than watch over the shipping tied up in St. Peter Port; for at the time of the Crecy campaign a party of household troops stationed there sailed out and captured a number of Spanish ships off Guernsey. Thus while the medieval Castle had its fair share of sieges and excitement, the less spectacular but constant protection offered to shipping was probably more significant. When the first tower designed for cannon was built c. 1435-7 it was built at the north-western extremity of the castle where it commanded both the inner roadstead and the approach to the Castle over the beach from St. Peter Port.
Castle Cornet, as it stood in the fourteenth and fifteenth centuries, clearly sufficed for medieval needs, though these were many. In addition to its military and quasi-naval functions, it provided a residence for the warden of the Islands, when he was in Guernsey, a centre for his administration and a prison.
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Castle Cornet, as it appears today, is predominantly a Tudor fortress. The Tudor constructions masked and the explosion of 1672 partly destroyed the medieval castle, and subsequent modifications are less obvious. (Le Patourel 1958)
