Certain examples can be found amongst the Royal Arms in England which show much earlier instances of dimidiation. The arms of Margaret of France, who died in 1319, the second queen of Edward I., as they remain on her tomb in Westminster Abbey, afford an example of this method of conjunction. The arms of England appear on the dexter side of the escocheon; and this coat undergoes a certain amount of curtailment, though the dimidiation is not complete, portions only of the hindmost parts of the lions being cut off by the palar line. The coat of France, on the sinister side, of course does not readily indicate the dimidiation.
Boutell, in his chapter on marshalling in "Heraldry, Historical and Popular," gives several early examples of dimidiation. The seal of Edmond Plantagenet, Earl of Cornwall (d. 1300), bears his arms (those of Richard, Earl of Cornwall, and King of the Romans) dimidiating those of his wife, Margaret de Clare. Here only the sinister half of his bordure is removed, while the Clare coat ("Or, three chevrons gules") is entirely dimidiated, and the chevrons are little distinguishable from bends. Both coats are dimidiated in other examples mentioned
by Boutell, viz. William de Valence and his wife, and Alianore Montendre and her husband Guy Ferre. On the seal of Margaret Campbell, wife of Alexander Napier, in 1531, the shield shows upon the dexter side the arms of Lennox, and on the sinister the dimidiated coat (the sinister half of the quartered arms) of Campbell and Lorn. This results in the galley of Lorn being in chief, and the Campbell gyrons in base.
An early and interesting Irish example of this kind of marshalling is afforded by a dimidiated coat of Clare and Fitzgerald, which now figures on the official seal of the Provosts of Youghal (Clare: "Or, three chevrons gules." Fitzgerald: "Argent, a saltire gules, with a label of five points in chief"). Both these coats are halved. They result from the marriage of Richard Clare, Earl of Hertford, with Juliana, daughter and heir of Maurice Fitzgerald, feudal lord of Inchiquin and Youghal.
An even more curious case of dimidiation comes to light in the arms formerly used by the Abbey of St. Etienne at Caen, in which the arms of England and those attributed to the Duchy of Normandy ("Gules, two lions passant guardant or") were dimidiated, so that in the former half three of the fore-quarters of the lions appear, while in the sinister half only two of the hind-quarters are represented.
Dimidiation was not always effected by conjunction down the palar line, other partition lines of the shield being occasionally, though very rarely, employed in this manner.
Certain curious (now indivisible) coats of arms remain which undoubtedly originated in the dimidiation of two separate coats, e.g. the arms of Yarmouth, Sandwich, Hastings, Rye, and Chester. In all cases some Royal connection can be traced which has caused the Royal Arms of England to be conjoined with the earlier devices of fish, ships, or garbs which had been employed by the towns in question. It is worth the passing thought, however, whether the conjoined lions and hulks used by the Cinque Ports may not originally have been a device of the Sovereign for naval purposes, or possibly the naval version of the Royal Arms (see page [182]).
One other remainder from the practice of dimidiation still survives amongst the presently existing rules of heraldry. It is a rule to which no modern authoritative exception can be mentioned. When a coat within a bordure is impaled with another coat, the bordure is not continued down the centre of the shield, but stops short at top and bottom when the palar line is reached. This rule is undoubtedly a result of the ancient method of conjunction by dimidiation, but the curious point is that, at the period when dimidiation was employed and during the period which followed, some number of examples can be
found where the bordure is continued round the whole coat which is within it.
The arms of man and wife are now conjoined according to the following rules:—If the wife is not an heraldic heiress the two coats are impaled. If the wife be an heraldic heir or coheir, in lieu of impalement the arms of her family are placed on an inescutcheon superimposed on the centre of her husband's arms, the inescutcheon being termed an escutcheon of pretence, because jure uxoris she being an heiress of her house, the husband "pretends" to the representation of her family.