The Rape was an administrative division of the county of Sussex.
The six Rapes of Arundel, Bramber, Chichester, Hastings, Lewes, and Pevensey were the primary divisions of the county of Sussex, intermediate between the county and Hundred. In this respect, they were similar to the Lathes of Kent and the Ridings of Yorkshire and Lincolnshire.
In other respects, however, they were dissimilar. Each Rape was a castlery, centred on a castle; each was in the hands of a single tenant-in-chief; and each had its own sheriff, who answered to the tenant-in-chief not the Crown: no royal sheriffs are recorded before the twelfth century. The Rapes also had an artificial profile, running in roughly parallel strips between the coast and the northern boundary of the county, each controlling one corridor of communication between London and the Channel. The vital routes between England and Normandy were therefore in the hands of six of the Conqueror's most trusted relatives or lieutenants; but no one or two of them could block his way.
The Rapes were not a Norman innovation since Domesday Book itself refers to their existence in 1066. Their characteristic features in 1086, however, mean that they had certainly been drastically remodelled in the intervening years, with military considerations uppermost in the minds of those responsible for the changes, a fact emphasised by the many references in Domesday Sussex to fragments of manors 'lost' to an adjacent Rape since 1066. Whoever carved out the new Rapes showed a cavalier disregard for the manorial structures of Anglo-Saxon England.
Just how ancient the Anglo-Saxon system had been is unclear. It may derive from the system of fortifications devised by Alfred the Great in the late ninth century to defeat the Vikings. It has also been argued that King Alfred's system may in turn have its roots in an earlier age. If so, the Sussex Rapes, like the Kentish Lathes, go back to the dawn of English history when their main function would have been to provide food-rents and military manpower to the king.
For more detail, see J.F.A. Mason, 'William the First and the Sussex Rapes', in 1066: Commemoration lectures (Historical Association, 1966); John le Patourel, The Norman Empire (1976); Stephen R. Bassett, The origins of the English kingdoms (1990); and Judith A. Green, The aristocracy of Norman England (1997).