associated - just as almost all southern Scottish castles are sited on the north side of their associated rivers19. In the west the stronghold of Carlisle, immediately south of the River Eden, formed the centrepiece of a relatively well thought out defensive system as long as it was in English hands, and especially after 1157. In a wide arc to the east and north of Carlisle were the baronial strongholds of BrampĀ¬ ton, Bewcastle, Liddel Strength and Burgh on Sands20. A fail-back line of sorts was provided by the fortresses of Egremont, Cockermouth, Greystoke, Appleby and Brough under Stainmore, but the true function of these castles was surely to serve as headquarters of local lordship rather than as a defence against the Scots21. If the Border was not in its earliest phase military, neither was it linguistic. A form of Old English speech had replaced Brittonic P-Celtic on the east side of the country, probably by the time Bede was writing his Ecclesiastical History in the 730s22. It is an interesting point in connection with the argument as to how 'real' the eastern Border or *East March' was that throughout the coastal plain of English Northumberland, between Tyne and Tweed, place-names of Celtic origin are comparatively rare, and names of English origin predominate23. North of the Border, however, the proportion of Celtic place-names increases markedly, although in Berwickshire the bulk of actual settlement names are Old English24. Inland from the coastal plain both south and north of the Border, the proportion of pre-Anglian P-Celtic place-names is appreciably higher25. But even in this hill country it seems to be the case that P-Celtic names have survived more successfully in the Scottish counties of Roxburgh, Selkirk and Peebles than in west NorĀ¬ thumberland (i.e. Redesdale, North and South Tynedale, West and East Allendale and Hexhamshire)26. By the twelfth century we can be pretty sure that a virtually single, undifferentiated dialect of Old English prevailed (or was in practice universal) from East Lothian southward to the River Wear: a story told of the siege of Wark Castle on the Tweed in 1296 turns on the identity of language among Scots defenders and English attackers27. 19 Barrow, G.W.S., "Frontier and Settlement" (as above, n.5), 19-20; Cadwallader Bates, The Border Holds of Northumberland (Newcastle upon Tyne, 1891). 20 Curwen, J.F., The Castles and Fortified Towers of Cumberland, Westmorland and Lancashire north of the Sands (Cumberland and Westmorland Antiquarian and Archaeological Society, extra ser. 16, 1913). 21 Ibid. 22 Campbell, A., Old English Grammar (Oxford, 1959), 4-5. 21 Mawer, A., Place-names of Northumberland and Durham (Cambridge, 1920). 24 Williamson, M., "Non-Celtic Place-Names of the Scottish Border Counties", unpublished Ph.D. thesis, University of Edinburgh, 1942; Watson, W.J., The History of the Celtic Place-Names of Scotland (Edinburgh, 1926), especially chapter 5. 2< Mawer, Place-names of Northumberland-, Watson, Celtic Place-names of Scotland. 26 Ibid. 77 Barrow, G.W.S., Robert Bruce and the Community of the Realm of Scotland (3rd edn., Edinburgh, 1988), 69. 202