[From Castle Rushen, Armitage Rigby, 1927]
HE narrow space between the curtain wall and the glacis is generally, but erroneously, called the moat. It is true that it occupies a portion of the original ditch, perhaps in places, about half of its width; but, as now seen, this space is not a moat, but a third ward, formed after cannon came into general use as siege implements.
The original ditch was evidently a very different affair. Such excavations as have been made suggest that it was much wider and deeper than at present. The surface of the hummock of clay on which the Castle was built slopes away from the wall as far as it has been followed, so that the lowest part of the ditch must have been some distance from the curtain wall, and may possibly have been deep enough for the river to flow almost round it. It was in fact a ravine chiefly natural, but no doubt improved by art. It is also quite probable that the ditch was wider towards the Market Place to counteract the disadvantage of the higher ground on this side.* At all events the Market Place appears to have been filled in at a later date for a considerable depth with shore gravel.
The question whether the moat was wet or dry is often asked and cannot be definitely answered as to its whole circuit. The part nearest the river was certainly wet, and that to a considerable depth at high tide. It is possible, even were the ditch not deep enough on the South side for the river to flow entirely round it, that it was supplied with water. The wells within the Castle could provide the necessary water which might have been contained by walls or banks crossing the moat, as was done at Brougham Castle.
It may be mentioned that there is a tradition that the moat was filled from a distant source, the water being led to it through wooden pipes, but this is highly improbable considering the excellent supply of water on the spot.
In looking up earlier descriptions of a building one is constantly met by statements impossible to reconcile with what remains. As a case in point, Dr. Oswald, writing about 1860, says: "The sluice which admitted water into the ditch from the harbour is still visible, built of rubble masonry in the same manner as the glacis."+ Allowing for the changes that have taken place in the last half century, it is still very difficult to imagine to what he could have referred, but as he seems to have mistaken the space between the curtain and the glacis for the moat, it is equally probable that he mistook the use of what he thought was a sluice.
The conversion of the ditch into an outer ward in the 16th century was a work of some magnitude. Tradition ascribes the change to Cardinal Wolsey, who was guardian to the infant 3rd Earl of Derby from 1508 to 1516. The reason for such an alteration was the growing use of cannon. Indeed the alteration seems to have been half a century behind the times. In " Castellated and Domestic Architecture of Scotland," McGibbon and Ross say that " Although gunpowder had been used to a considerable extent during the 14th century, it was not till the 15th century that it was made available in the form of siege artillery. About the year 1400 cannons were employed chiefly in the field against troops. By 1430 the royal armies had begun to use cannon against fortresses, and by the middle of the century it was recognised as a principle in the construction of castles that they should be built so as to resist artillery. For some time efforts were made to defend castles against artillery by the erection of outworks, like barbicans, in front of the gates. These were armed with guns, the loopholes being pierced at the base of the walls, so as to keep the guns of the besiegers at a distance and so save the walls" .....
This describes fairly well what was done at Castle Rushen by the erection, first, of the barbican and then of the glacis. As pointed out in Chapter II, the first idea, on the introduction of cannons, seems to have been to further defend the entrance. Later on it was seen that the curtain wall rising unmasked from the scarp of the ditch would be of no avail if attacked by heavy guns. It is only 7 feet in thickness, and exposed a height varying from 25 to 40 feet, a fair target even for a 16th century gunner. To protect this important wall a glacis must be erected; and, to be effective, it must be within a few yards of the wall it was to protect, as the cannon of the period had a high trajectory. In order to get it near the curtain, the ditch was first filled in, and then the glacis was erected on the filling at the proper scientific distance from the wall it was designed to protect.
But offensive requirements were not forgotten, for at three important points drum towers were erected, rising from the glacis and fully armed with cannon.
Of these towers, that facing the sea seems, judging from old sketches, to have been a plain drum with flat roof. There is only enough of the foundation left to mark the spot it occupied.
The tower on the town side has also disappeared. It seems to have been generally similar to that last described, except that it had a square annexe covering a pastern. This door is probably the " sally port" referred to in an account of the siege of the Castle by the parliamentary troops under Colonel Duckenfield in October, 1651. Moore's history says: " News came that there was a discontent generally among the souldiers in the Castle, some of whom on the 31st wrenched open a sally-port by the help of some of the Parliamentary troops, who thus became possessed of the outward wall and tower." This sally-port must not be confused with that near the gable of the Derby House. The outer wall of which the Parliamentary troops became possessed was the glacis with its three towers, and the pastern.
This second tower seems to have been standing until about 1840, and is remembered by one or two of the oldest inhabitants. It is said to have been called the Baby Tower in late times, owing to its being used as a playroom by the children of one of the Governors.
The third tower on the line of the glacis still exists near the harbour. It was at the angle formed by the return of the glacis towards the curtain wall. Whether this tower was built at the same time as the glacis is uncertain. In favour of the supposition that it was, are the facts that it exactly occupies the angle mentioned above, and that without it this part of the outer defence would be very weak. On the other hand there is no sign of its having been fitted with cannon, and it appears to have had wooden floors and a conical roof overhanging the walls so as to leave no room for cannon. The ground floor has two double loops which seem to be meant for hand gun fire, but the upper floor shews no sign of defensive arrangements. Probably the tower was originally built with the glacis, and the upper part rebuilt at a later date to serve more peaceful purposes than those for which it was originally designed; and the appearance of the masonry also suggests this.
The ground floor is only slightly above high tide level, and while the greater part of the ditch was filled in to the level of the main ward, the part near this tower seems to have been only filled in to about high tide level. The reason for leaving this portion lower than the rest is not very apparent, but may perhaps be partly explained by its being protected by the river. A further explanation may be that as an attack on this side would probably be by boat, it was advisable to be able to post cannon near water level instead of having to fire downwards from a height, for it was not only difficult but very dangerous to fire the early cannon in any position other than horizontal.
Indeed the risk to the gunner seems to have been considerable in any case, judging from an extract from a 15th century book on Artillery, quoted by Boutell in " Arms and Armour." The author points out that it is most important for the gunner " to know and to fear and to love God, and have always before his eyes the fear of offending Him, more than the fear of all other men of war whatsoever. For whenever they fire a bombard, cannon, or any other piece of artillery, or that they desire to make use of gunpowder, their great strength and force constantly cause the cannon which they fire to burst; and if the cannon itself do not burst, there always is a risk of being burned by the powder, if he is not very cautious, and does not use a good discretion for his own preservation and safety." Truly there was something very heroic about the mediaeval gunner.
On the sea side of the Castle the glacis is stopped by the barbican which was well loopholed both for cannon and hand guns.
The sally port in the curtain wall was probably enlarged to its present size when the glacis was erected to give free access from the main to the new outer ward.
It is clear then that early in the 16th century the arrangements and appearance of the Castle were considerably altered, and the building seems to have preserved its new form without any material change (except the erection of Lord Derby's house in the main ward) until taken by Cromwell's men in 1651. It is probable, however, that the outer ward had lost some of its purely military character before this time. The placing of the entrance door of Lord Derby's house (built 1644) at the end of the building, close to the enlarged sally port, suggests that the outer ward was used as the private approach to the Castle by way of the pastern attached to the middle of the three towers on the glacis. It is likely that at this time such space in the ward as was not required for military uses was laid out with herbs and flowers.
In 1652 this ward is described as the " garden or ditch." The Malew parish register of that year states that Captain Smith, Deputy Governor, was buried on June 27th " in the garden or ditch of Castle Rushen." Ninety years before this (1561) it was ordered that " the clerk of the garden is to be appointed in either of the said houses (Castles of Rushen and Peel) by the receivers thereof, the same to be such as they will answer for."* It is hardly likely, however, that an appointment, carrying the high sounding title of Clerk of the Garden, would be made for attending to the small strip of ground in this ward, and we may suppose that some of the ground without the walls was cultivated as demesne land, but it is probable enough that even then this sheltered spot was found good for pot herbs.
*At the Tower of London the ditch was widened considerably on the Tower Hill side to minimise the command from that eminence.
+ Vestigia. Manx Society, Vol. V, p. 91.