The first fort on the site was built by the Duke of Cumberland. Although there did previously exist an earthwork battery on the site, built in 1714. Work on Cumberland's fort commenced on January 1, 1747, and was substantially complete by the end of 1748. The fort had an irregular star shaped form, and was of earthwork construction. In section, the defences comprised a glacis, banquette and covered way, a dry ditch, berm, rampart, parapet and terre-plein. Within the body of the fort, a number of brick buildings were constructed, comprising a guardhouse, storeroom and powder magazine; of the two proposed barrack blocks, only one is believed to have been completed.