very limited in scale. In 1533, Henry broke with Pope Paul III in order to annul the long-standing marriage to his wife, Catherine of Aragon and remarry. Catherine was the aunt of Charles V, the Holy Roman Emperor, and he took the annulment as a personal insult. This resulted in France and the Empire declaring an alliance against Henry in 1538, and the Pope encouraging the two countries to attack England. An invasion of England appeared certain. In response, Henry issued an order, called a "device", in 1539, giving instructions for the "defence of the realm in time of invasion" and the construction of forts along the English coastline. Sandgate was intended to defend a vulnerable point along the Kent cliffs, just west of Folkestone, where an enemy force could potentially land and make their way easily further inland. Sandgate's construction was supervised by the Moravian engineer Stefan von Haschenperg, and Thomas Cockys and Richard Keys acted as commissioners for the project. In the initial stages of the work in 1539, a team of 237 men were employed, with masons, quarrymen, limeburners and wood fellers preparing the site; the masons were drawn from as far away as Somerset and Gloucestershire. By the summer, over 500 were at work, including labourers, bricklayers, carpenters and sawyers. After a pause during the winter months, work picked up again in the summer of the next year, with 630 working on the castle that July. The castle's foundations rested on the underlying shingle of the beach. The walls were made from Kentish ragstone, mostly roughly laid, with some work using finer ashlar, with Caen stone used in the detailing. Most of the ragstone was collected from the local beaches, where there were suitable outcrops to the west and east of the site. 459 tons of Caen stone was recycled from the priories of Christ Church and Horton, which had recently been dissolved by Henry. In total, 147,000 bricks were used, produced at 13 different brickyards, and 44,000 tiles, mostly manufactured in Wye, along with 1,829 loads of lime, 110 tons of coal and 979 tons of timber. The total cost of the project came to £5,584. At the centre of the new castle was a circular keep, with three ovoid towers and bastions around it on the northwest, northeast and south sides, and a gatehouse to the north. These were surrounded by two curtain walls,