A survey of the coastal castles of the West Highlands in relation to their siting led to the following conclusions:
1. The siting of the majority of W. Highland castles in relation to the sea has enough common features to suggest that they derive from a common technological tradition. Castles on larger inland lochs such as L. Awe seem to share this tradition. There are some exceptions, particularly the Campbell castles of Argyll like Kilberry and Barcaldine: these are sited slightly back from the shore and do not relate to it in the same way as the majority.
2. Good seaward visibility is a common feature. Castles that can be said to ‘command’ sounds and sea lochs are normally sited to have unobstructed views across, up and down the passage in question. In some cases this has led to groups of castles being intervisible, and traditions of chains of watch fires have survived e.g. for the MacDougall castles of the Sound of Mull. These may be genuine but it does not follow that signalling was the main reason for the siting: seaward visibility was clearly a decisive factor in the siting of some castles that are out of sight of any other (e.g. Claig Cas., Sound of Islay). This allows hypotheses on what ‘commanding’ a sea passage actually meant. Cannon were unavailable before the 15th century and only rarely, as at Kyleakin, would physical blocking of the passage by a boom have been possible. It seems more likely that castles like Claig and Ardtornish were both manned lookout positions and bases for fast oared boats that could intercept unfriendly vessels trying to force a passage. This would require associated harbour facilities, which are indeed universally found (see below).
3. Some of the larger castles are situated where a land route meets a sea route, as at Inverlochy. Others are in hidden locations difficult to approach from the seaward without local knowledge, like Cas. Tioram. Piracy may have been a factor in the siting of the latter group.
4. The harbour facilities associated with W. Highland castles are as follows
(a) Almost universal: a well-sheltered beach, cleared of big stones if necessary and suitably shelving to allow small boats to be launched and recovered quickly at any stage of the tide (Gaelic Puirt). The space available above HW is in some cases sufficient only for boats of 6-8 oars. The cleared beach is sometimes at a distance from the castle e.g. Lochaline, and is not normally close enough to ensure that the boats would be protected and accessible with the Castle under siege from the landward.
(b) Normally present: a deep-water landing place (Gaelic Lamhraig) on the seaward side, where a vessel of moderate draft could come alongside at any state of the tide. Usually so situated that the protection (e.g. archery) could be provided for people arriving or leaving that way, but the castle entrance does not normally face in that direction so they might have to come over the wall.
(c) Occasional: a reasonably sheltered anchorage for vessels too large to be hauled out (Gaelic Acarsaid). It is interesting that this facility is available only at a minority of castles, as the Hebridean vessels even of birlinn size must normally have lain afloat.
(d) Uncommon: a few of the castles have, at a distance of up to 2km or so, a more or less landlocked pool accessible only with difficulty at HW; perhaps suitable for winter mooring of galleys.
5. There is no sign that this tradition in siting castles has roots in the Iron Age. Coastal duns and Iron Age forts are not in general sited on the same principles, although obviously some sites were re-fortified later. Nor have I been able to trace any clear connection to Viking sites, although the evidence is fragmentary. There are however many connections to the siting and harbour facilities of contemporary castles outside the W. Highland region, especially to the Welsh castles of Edward I.
Mike Jarvis