Edward’s policy, on his return from the East, and accession to the throne, led him not to build, but to pull down castles. In the fourth year of his reign it was enacted: “It is to be enquired of castelles, and also of other buyldings girt with dytches, that the walls, tymber, stone, lead, and other manner of coverynges are worth, and how they may be solde, after the very value of the same walles and buyldinges. And how moche the buyldinges without the dych may be sold for, and what they may be worth, with the gardens, custylages, dove house, and all other issues of the court by the yere.” Probably this mainly related to such unlicensed castles as had escaped the hands of Henry, as none of the older or more important structures were then pulled down. Many of these, indeed, had recently been augmented and embellished, and where it suited his convenience, Edward followed in the same track, strengthening and repairing decayed walls and towers, and adapting them to the changed circumstances of the time. Thus, at Porchester, he rebuilt the inner ward, and much enlarged the contained buildings. The additions to Middleham, an outer ward and gatehouse, are of his reign, and the vast outworks beyond the lake at Kenilworth, and the effect of these and similar alterations was to convert the original castles into those of the concentric type. But it was in North Wales that circumstances called forth Edward’s talent as a military engineer. In that country the strong places were hill camps, unfitted for modern warfare, and out of the line of his operations. He found there neither English mounds nor Norman keeps, and his works are not only on a grand scale, but they are original. To him are entirely due the castles of Conway and Caernarvon, Beaumaris and Harlech. Possibly Bere Castle and Dolbadarn Tower were strengthened by him, but they rather resemble the early works of his father. In Scotland Edward’s works have been mostly destroyed, but his hand may be recognised at Linlithgow, possibly in the castle at Edinburgh, and in the old fortifications of Berwick.