The name is the Normanized Anglo-Saxon for CNIHT meaning knight. At the time, it did not have its medieval significance. It denoted who served the warrior chief, as a youth or squire on the tribal level. The name was applied from an early time of occupation, not to a Saxon but to a Dane who came from Dane law at the time of King Cnute to serve as a marcher lord for the wild fastness of Cornwall, the centre or its border with Devon at Launceston.
In the reign of Edward the Confessor, the Earl of Wessex, Godwine, had first married Gytha a Dane and second, a daughter of the Danish King Swein, previous conqueror of England and father of King Cnute. He arranged to have his sons granted Earldoms covering all of England south of the Midlands and Northumberland. This family was banished for a few years, but returned in 1053 to assume near complete control of the government.
The Confessor although a celibate, married Harold Godwineson's daughter and the latter took over as Earl of Wessex at his father's death in l053. Thane Othmarus Le Knevet was marcher Lord and Constable at Launceston, Cornwall under Harold Godwineson and his father. His stronghold was Dun-hevet or the "chief".
Although the record of this holding is in the Norman Property Surveyor Description known as the Doomsday Book, the remains in the late 17th century was a jumble of several successive styles. It is the only Norman castle in England or elsewhere that had a square bailey with outer walls, whose form and size is certainly that of an early Roman military camp.
The Romans held formal control of Devon from Exeter and there is no record of permanent settlement by the Romans in Cornwall, although early records are far from complete. Ptolemy records a settlement at Tamara on the Tamar River about l50 AD. This is very likely the site of Dun-hevet, since this is the first ford for crossing the Tamar between this centre of the peninsula and the sea. It is a likely point for defence of Devon and for incursion into Cornwall.
An early defence post would be constructed of wood with ridges and ditches round about. Thorough Norman razing and castle construction with footings of stone would leave little evidence of previous structures even with Archaeological sectioning methods. The form suggested by the terrain would be an obvious base for rebuilding. In one corner of the Roman square is a Celtic, conical tor, like the one at Glastonbury. One descriptive source says that the hill at Dun-hevet had no castle on its top from the conquest of the Saxons until the Normans came.
Castles as we know them are a Norman specialty for defence. This does not preclude the use of the area with ridges and ditches for a Saxon stronghold with housing, all of wood construction. The tor could be used as a final defence point possibly with a wood defence structure that would deteriorate, surrounded by ditches. The main gate to the bailey, facing the drawbridge over an extensive moat, had a rounded Norman arch on the outside and a pointed arch on the inside.
William the Conqueror defeated King Harold Godwineson and his Thanes, massed in Saxon fashion, on Telham Hill north of Hastings in 1066, surrounded by ditches filled with brush on the defense side. Although the Saxons accepted William on his coronation at Westminster on Christmas day, rebellions arose in 1067 in the North and Southwest. In quick sweeps the rebels were defeated. Dun-hevet was wasted or destroyed to one-fifth of its former value and Brian of Brittany replaced Othomarus Le Knevet and became the first Earl of Cornwall.
When William returned to Normandy in 1068 he took the marcher, Le Knevet, with him. He arranged a marriage for Othomarus with the Norman heiress Dammartin and gave them St. Pierre, a few miles from his birthplace at Falaise so that his uncle Walter could watch over his Normanization. This hold took the name Canevit and the family name Canivet took on the Norman meaning of Marcher or border guard. In 1075 Brittany rebelled against Duke William's overlordship. Dun-hevet, back in Cornwall, was given to Robert, Count of Mortain, half-brother of William, with the title of Earl of Cornwall.
Since we find no record of the family in the Latin Pipe Rolls of early Norman English times, it is assumed that they remained in Normandy for several generations under the watchful eye of the Norman kings and their adjuncts in Normandy. Between 1180 and 1195 the third generation at St. Pierre de Canevit included Richard and William de Knevet, named after members of the royal family. These men fought for Normandy and England against France. About this time members of this family acquired property in England. With the conquest of Normandy by France, some removed to England and some to Amiens in Piccardy near Flanders to become wool merchants dealing with England at London.