A purpose-built platform for two 15-inch guns

Roberts and Abercrombie were specialized fire-support ships. Their elevated single turret, modest 12.5-knot speed, and broad hull all followed from that role. Two geared turbine shafts and two boilers supplied the speed needed to move between bombardment stations, while four twin 4-inch mounts, pom-poms, and up to twenty Oerlikons provided a layered defensive battery. The 15-inch turret carried much heavier protection than the four-to-five-inch belt because the guns and their working spaces were the ship's decisive asset. The comparison between the ships also shows how closely related designs could differ by several hundred tons while retaining the same core concept. John Brown at Clydebank built Roberts, while Vickers-Armstrongs at Wallsend built Abercrombie; a crew could number about 460 despite the class's narrow mission. Roberts commissioned in 1941 and Abercrombie in 1943, putting an old ship type back into service for a new amphibious war.