The work was originally designed with a semi-circular gun platform and two blockhouses at the rear; however, it was eventually built with a semi-hexagonal front. Consequently, the landward defenses incorporated a free-standing red-an trace with thick walls and numerous musketry loopholes, which were shielded by two flanking traverses. The land front itself was protected by a shallow ditch. A solid blockhouse with battered walls occupied the center of the enclosure. In 1770, St. Anthony's Battery had an armament of three 8-pounder guns with 427 rounds of roundshot and 75 rounds of grapeshot; and eight 6-pounder guns with 127 rounds of roundshot and 45 rounds of grapeshot.