Nullus constabularius distringat aliquem militem ad dandum denarios pro custodia castri, si facere voluerit custodiam illam in propria persona sua, vel per alium probum hominem, si ipse eam facere non possit propter rationabilem causam; et si nos duxerimus vel miserimus eum in exercitum, erit quietus de custodia, secundum quantitatem temporis quo per nos fuerit in exercitu.
No constable is to distrain any knight to give money instead of performing castle-guard, if he is willing to perform that guard in person, or, if he is unable to do it for a satisfactory reason, through another reliable man. And if we have led or sent him in the army, he is to be quit of castle-guard in proportion to the time he is in the army at our behest.
Please note: commentaries are presently available only for clauses marked with *; more commentary to be added in due course.
Clause 29, like Clause 28, was concerned with castles, not with supplies this time, but with their manning, and how that was organised and financed. It is complicated by the fact that it contains two provisions dealing with different issues, separated in the text by a change of voice. The first was concerned solely with the way castle-guard – essentially garrison duty – was performed, and was phrased in a way which could have made it applicable to all castles, not just royal ones. The second related explicitly to demands for castle-guard made on men who had also served in the royal army, and the constraints it imposed therefore concerned the king alone. In fact the king was probably the essential target of both parts of the clause, but the possibility that it was intended to have a wider application should be kept in mind.
Castle-guard, the duty of serving for specified periods (usually up to forty days) in a lord’s castle, was one of the services which a knight might have to perform at the command of his lord, whether the latter was the king or a baron. It was not required at many English castles (the Tower of London, for instance), which were instead manned by paid soldiers, and where it was demanded it had usually been commuted for cash by the end of the twelfth century. The money raised in this way could then be put towards the cost of hiring a mercenary. Castle-guard at Dover was owed from nearly 120 knights’ fees, mostly in Kent but also in at least six other counties. Calling on these widely distributed men, who were only liable to serve for about six weeks every year, was hardly the best way to provide a garrison for arguably the most important castle in England, and by 1215 it had come to be manned by paid soldiers who could remain in post indefinitely, as, indeed, they had to do – Dover Castle played a vital part in defending the realm in the civil war at the end of John’s reign, when it was under siege for months at a time. The rates at which castle-guard service was commuted for cash seem certain to have been increased in the years leading up to Magna Carta, partly because of a rise in the levels of soldiers’ pay and partly simply because the king needed more money. Clause 29’s stipulation that knights who were willing to perform this service in person should be allowed to do so was audacious in giving the tenant, not the king, the right to decide how a service owed by the former to the latter was to be performed. Its potential effects were two-fold. It deprived the king and his agents of a way of raising money. And it also threatened them with the possibility that the garrisons of some important castles would at least partly consist of soldiers whom they had not chosen and whose loyalty could not be guaranteed – well over a third of the tenants of Peterborough Abbey who owed castle-guard at Rockingham Castle, Northamptonshire, rebelled against King John in 1215/16.
The second part of Clause 29 addressed what was seen as a different though related abuse, the king’s practice of demanding castle-guard on top of military service in the army when he called out the latter. It was commonplace for knights to owe both castle-guard and host duty, but evidence which includes exemptions from castle-guard granted in 1214 to two men then in the king’s army in France suggests that John was in effect requiring such men to perform these two forms of service simultaneously, and compelling them either to commute for cash, at a doubtless extortionate rate, or to provide a substitute soldier for, the one they did not do. The second part of Clause 29 did not abolish dual services, but treated them as effectively two parts of a single service, perhaps limited to forty days altogether, so that after 1215 the time which was owed for garrison service was reduced in proportion to the time spent as a knight in the field.