Princess Anne’s Battery is on the hillside above the harbor. The site is sometime referred to as Princess Caroline’s Battery, Princess Amelia’s Battery, or even Princess Royal’s Battery. These three battery names, however, refer to 18th and 19th-century batteries located in and around Princess Anne’s Battery. Princess Anne’s Battery was constructed in 1732 to mount five 12 pounders, and saw action during the Great Siege. During the 19th century, Princess Anne’s Battery was rebuilt to house four 12 pounders and three 13-inch mortars.
In 1942 it was proposed to increase the antiaircraft defense of Gibraltar by mounting seven 5.25-inch guns, three on Europa Point and four at Princess Anne’s Battery. The 5.25 QF Mk Is were dual-purpose guns, built for twin mounts on Royal Navy cruisers and battleships. The British Army took the basic design and upgraded it into the Mk II, with a stronger breech ring to allow a muzzle velocity of 2850 f/s as opposed to the Mk I’s 2672 f/s.
The four 5.25 QF Mk II guns on IB mountings did not become operational until 1956. Shortly after becoming operational, the four guns were reduced to caretaker status and declared surplus in the 1990s. The guns could fire ten, 88-pound shells per minute skyward to 55,000 feet, or horizontally to 27,000 yards or 13.5 miles. The Mk IB mounting has an enclosed gun shield, while the shield for the IA mount was open in the rear. The four guns of Princess Anne’s Battery are each partially enclosed by a concrete wall. Guns Nos. 1, 2, and 3 have a semisunken magazine, while gun No. 4’s magazine is completely below ground level. To the rear of Gun No. 2 is an entrance into Willis’ Gallery, a segment of Gibraltar’s 30 miles of underground tunnels.
Princess Anne’s Battery was named after the eldest daughter of George II, Princess Anne, Princess Royal of Great Britain and Ireland. She is better known as Princess Anne of Orange due to her marriage to Prince Willem IV of Orange-Nassau.