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The Rock of Gibraltar:
Fact or Fiction?

By Kevin Canada
June 2013

The name Gibraltar has been synonymous with "invincible" for centuries. Its forbidding presence at the southern tip of Spain long served as a material reminder of Great Britain's dominance over the Western Mediterranean and Eastern Atlantic. During World War II this image was reinforced by clever propaganda as well as material improvements. War posters showing the bristling batteries of Gibraltar, prepared to defend against all comers, graphically underscored the popular ideal of the fortress. Modern books such as Das Boot illustrated the very real dangers posed by Gibraltar-based anti-submarine warfare units to German U-Boat commanders.

Wargamers have also indulged in perpetuating the ideal of "The Rock," frequently portraying it as a huge fortress, comparable to the Maginot Line in its complexity. In naval simulations it’s often a literal cork on the west end of the Mediterranean, preventing Italian surface sorties into the Atlantic, or German warships from entering the Mediterranean.

Considering the repeated failures of other famous fortresses across the globe, there is some cause for wondering just how "invincible" the Rock of Gibraltar really was, and just how capable it would have been in stopping a modern siege or a move by an enemy fleet to bypass it.

The Pillar of Hercules

Physically, Gibraltar is a limestone mountain rising some 426 meters from sea level, dominating the Straits of Gibraltar, which are less than 16 miles across to Spanish Morocco. The entire territory is less than a kilometer wide and five kilometers long. Along its western side is Gibraltar Bay, where the Port of Gibraltar is located, with a breakwater and facilities almost 50% as large as the territory itself. The mountain itself is honeycombed with 34 miles of tunnels dug into the rock by the British over the years, providing cover for numerous gun emplacements, hangars, storage facilities, barracks, hospitals and thousands of troops.

Militarily, the fortress was used primarily as a naval base and air station, since its limited size allowed it to support a garrison of only 15,000 ground troops. The one airfield, running across the length of the peninsula at the northern extreme of the territory, was expanded into Gibraltar Bay starting in 1937 and completed by 1942. This allowed support for nearly 100 fighters and several squadrons of medium and heavy bombers, and allowed Gibraltar to act as a vital staging point for aircraft transferring into the Mediterranean theater. Anti-air defenses were substantially improved during the war. In 1940, there were some 20 3.7" guns, four 4" guns, 10 40-mm Bofors and two pom-poms, plus numerous searchlights. 1942, this complement had been increased to 30 3.7" guns and almost 20 Bofors.

The naval base at Gibraltar had been built before World War I as a response to German pretensions toward becoming a naval power. By 1939 it was one of the most important British naval facilities outside the home islands, providing a relatively secure anchorage and repair facility for the British Navy. This was the home port for Somerville's Force H, which gave the British Navy an extraordinary ability to project its power into the Western Mediterranean and successfully contest the Italian Navy's attempts to control the sea.

Making the Rock a hard place: British anti-aircraft gunners.

The seaward defenses of the fortress were quite varied but, while formidable, not quite the propaganda image of the Rock, bristling with guns. The primary batteries were a set of twin 9.2" naval guns guns at the southern end of the peninsula, which had sufficient range to interdict all surface naval traffic through the straits. Six more single-gun batteries of 9.2" naval guns were placed facing seaward to the east. Finally, a twin 9.2" howitzer battery faced the straits as well.

The secondary batteries were just as numerous, with eight 6" naval guns, although three of these faced northward, toward the border with Spain. A tertiary armament of four 4" guns in two batteries protected the eastward cliffs.

“Conquerable by No Enemy”

Despite these formidable assets, the Allies themselves considered the fortress highly vulnerable. They expected that any concerted Axis assault would cause the fall of the position in at best two weeks, at worst a few days. Indeed, prior to the Operation Torch landings in North Africa in late 1942, the Allies worried that the Spanish garrison bordering Gibraltar — about 33,000 troops — could quickly be augmented by 20,000 German military personnel covertly placed inside Spain in anticipation of an attack on the fortress (some estimates placed this as high as 80,000). Allied planners greatly feared a Crete-style air assault, especially in conjunction with a determined ground assault.

Gibraltar was extremely exposed to artillery and air bombardment, with three major Spanish artillery batteries (one in North Africa at Mount Hacho, two near Algiceras — only five miles away from the port) positioned to blast the "Rock" into rubble, collapsing its tunnels and destroying its exposed heavy batteries, as the Japanese had done at Corregidor in 1942. Incidentally, one critical asset, water, was only available from collected rain water runoff, as there was no other natural source of potable water on the Rock itself.

Throughout the war, Italian airmen bombed Gibraltar with mixed success. Moreover, the all-important airfield was only a few hundred yards from the border with Spain, which left it extremely vulnerable to bombardment from Spanish-controlled positions, which could give the Axis control of the air until sufficient Allied aircraft carrier sources might (eventually) be brought to bear. Finally, while the port itself was very well protected, the bay — used as an anchorage for merchant shipping throughout the war — was infiltrated on numerous occasions by Italian frogmen operating from the battered Italian freighter Olterra docked on the Spanish side of the bay, successfully sinking some 42,000 tons over two years.

Given this apparent vulnerability, one wonders about the "invincible" status traditionally conferred on Gibraltar by historians and wargamers alike. The rather light gun batteries placed on the fortress do not appear to have been much of a threat to battleships. Even heavy cruisers would more than likely have been able to pass under Gibraltar's guns with only light damage, at worst.

In part the myth seems to have been perpetuated by the simple fact that using naval assets to bypass the "Rock" was apparently never seriously considered by Germany or Italy during the war. Certainly the Italians had no strategic reason for deploying their scant battlefleet (short on fuel, as always) beyond the Mediterranean — such an act would have been an unacceptable concession of sea control to the British, and ended definitively any pretensions of an Italian Empire in Africa for Il Duce.

Likewise, the Germans would never have committed elements of their even smaller surface fleet to be potentially trapped in the Mediterranean. Had the Axis had greater forces at their disposal — say, through the successful seizure of the French battlecruisers Dunkerque and Strasbourg — there might have been a reason for a deployment from the Mediterranean to the Atlantic.

When looked at broadly, the greatest strength of Gibraltar was from its strategic position at the western mouth of the Mediterranean, and the well-developed naval and air facilities which the fortress protected. These combined attributes, rather than any physical "punch" from the fortifications themselves, provided the real deterrent. The narrowness of the straits contributed significantly to Gibraltar's strength, since there was little room for an opponent to avoid air or naval forces that could be easily concentrated to confront an intruder. The difficulties encountered by even German submarine forces attests to the risk of running past a station where strong ASW units are very near their base.

Throughout the war, Britain garrisoned Gibraltar with many of its most important naval assets: The Rodney, Hood, Ark Royal and Renown were variously stationed there. Most of the critical Malta resupply/reprovision convoys started from Gibraltar, and were able to enjoy the cover of its air umbrella for the first third of the journey. By late in the war, Allied air-based ASW patrols extended almost to the Azores, and severely curtailed Donitz's ability to threaten Allied shipping after 1943.

The images of Gibraltar in history, propaganda and wargames as an invincible fortress are thus probably overblown. It makes sense, for example, to allow an Axis naval unit to pass by Gibraltar unimpeded in a game like Third Reich should the Allies fail to sufficiently garrison it with air and naval units to block the enemy's way. Conversely, it makes no sense to allow an Allied player to stack whole armies in a territory less than four miles square!

The real-war concerns of the Allied military planners makes sense when one concedes that it can be (realistically) garrisoned with only three brigades. Indeed, had Gibraltar faced the same kind of assault its cousins like Singapore and Corregidor had to face in WWII, there is a very strong likelihood it would have faced a similar fate. As it was, Gibraltar was allowed to keep face, and its status as the invincible Rock.

Gateway to Bomb Alley

As a variant for Second World War at Sea: Bomb Alley, should the Axis player seek to move any surface ships through the Straits of Gibraltar (zone F20), the Allied player may force surface combat from the guns of Gibraltar against the Task Force attempting passage.

The fortress gunnery values are 2-5-4, with all hits from Allied primary and secondary guns considered plunging fire due to the altitude of Gibraltar's guns. All to-hit rolls are +1, reflecting the advantage of shore batteries using pre-registered fire areas.

The Allied primary and secondary batteries are considered to have light armor and tertiaries have no armor; however, it takes TWO hits in a single round by any given ship to equal one "normal" gunnery hit against any shore battery. If only one hit is scored by a ship in a round, then the fire has no effect. This reflects the fact that Axis commanders had little intelligence on the exact placement of Allied gunnery positions, and would have to rely heavily on best-guess visual spotting for anti-battery fire.

If using the tactical map, zones Z13-A1/A1-Z21 are considered land, as well as Z9-Z5. Gibraltar is considered to occupy zone A1. All Allied primary batteries are restricted to a maximum range of three hexes on the tactical map.

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