In the early years of the Second World War, beach areas around Northern Ireland became potentially vulnerable to attacks. Some believed the threat of Nazis landing in Ulster all too plausible. Beach defences sprang up around Magilligan, Dundrum, Strangford, Carnlough, Cushendall, Cushendun, Portrush, and Portstewart.
Not far from Magilligan Point, the pillbox in the townland of Bennaress overlooks much of Downhill Beach. As a potential amphibious landing site, the beach would offer two exits leading to the nearby cliffs. From the site, an observation port looks north into the Atlantic Ocean. Machine gun positions face east and west covering the length of the beach.
The construction of the pillbox is unique in Northern Ireland. As well as the standard reinforced concrete, the pillbox makes use of brick and locally-sources basalt rock. This would provide excellent camouflage but the 60cm-thick walls would not be blast-resistant. While the rock may have deflected bullets, a targetted attack on the pillbox would have proven fatal for the crew inside.
The Bennarees pillbox at Downhill is accessible by car, as visitors can drive onto the strand. It stands next to a lifeguard tower on the beach, highlighting its great position for having a commanding view of the sea and sand.