The usual model of the 3-in (76.2- mm) gun in use with the BEF in 1940 was this platform version, complete with twin axles. The platform used outriggers when firing and the feet for these can be seen below the gun platform. The locker housed ready use ammunition and the sights.

The genesis of antiaircraft defense appeared soon after man took to the air. There are reports of balloon and anti-balloon artillery in the American Civil War and the Franco-Prussian War, and in 1890 the Russians tested a field-gun battery against a balloon moored three kilometers away. The first aircraft downed in combat fell to ground fire in the Italo-Turkish War of 1912; so when World War I began, there were precedents for ground-based air defense systems.

During the war, both sides bombed their opponent’s cities. The bombing of London and Paris by the Germans tied down considerable Allied resources, estimated in the British case to be eight times the resources expended by the Germans. British defenses claimed 21 airships (of 201 airship sorties) and 27 aircraft (of 424 aircraft sorties), of which ground fire accounted for three Zeppelins and 11 to 13 aircraft. In November 1918 the British used 480 antiaircraft guns and 376 aircraft in the defense of Great Britain. Nevertheless, aircraft flew primarily in support of ground forces. On the Western Front, German antiaircraft gunners claimed 1,588 Allied aircraft, while French gunners claimed 500 German aircraft; Italian gunners claimed 129; British Expeditionary Force gunners, 341; and US gunners, 58. The guns grew increasingly effective as hastily improvised equipment gave way to specially designed equipment, while, relatively speaking, aircraft showed only modest improvements in performance. The number of German antiaircraft rounds for each claim fell from 11,588 in 1915 to 5,040 in 1918. Similarly, French rounds per claim de- creased from 11,000 in 1916 to 7,000 in 1918, and British rounds per claim fell from 8,000 in 1917 to 4,550 in 1918. American antiaircraft artillery downed 17 German aircraft in three months, averaging 605 rounds per kill.

In contrast to World War I, the air defenders made little progress between the wars. The three-inch gun of World War I dominated what little antiaircraft artillery there was, and acoustical devices provided the best location equipment. In 1928 the United States adopted as standard equipment the three-inch M3 gun with a muzzle velocity of 2,600 to 2,800 feet per second (fps). It had an effective ceiling of 21,000 feet, just exceeding the 17,000-foot aircraft ceiling of the day. Meanwhile, new technology-such as removable barrel liners, automatic breech mechanisms, and continuous fuze setters-improved the antiaircraft guns. But the revolution in aviation technology of the 1930s, permitting much greater aircraft speeds and altitudes, rendered three-inch guns and acoustical-location gear obsolete. In the latter half of the 1930s, new equipment began to appear in antiaircraft units around the world. The major powers adopted slightly larger but much more powerful guns, settling on about a 90-millimeter (mm) gun with a muzzle velocity of 850 to 900 meters per second and a rate of fire of 30 rounds per minute (rpm). The Germans chose the 88-mm triple-purpose gun, the British built a prototype 3 .7-inch gun in 1936, and the Americans began to replace their three-inch gun with a 90-mm gun in 1940. All major powers experimented with new detection devices, but it was the British who forged a lead in the field of radar.

British Antiaircraft Artillery

The British had the most acute air defense problem. Of all the European capitals, London was easiest to find and closest to the border. In Winston Churchill’s colorful words, the British capital was “a tremendous fat cow . . . tied up to attract the beasts of prey.” The British convinced them- selves of the decisiveness of air power, fearing what they called the “knockout blow.” They accepted the dismal prophecies of theorists such as the Italian Giulio Douhet, the Briton Sir Hugh Trenchard, and the American William “Billy” Mitchell who predicted that the employment of air power would result in devastated cities, pulverized industries, and panic-stricken civilians. These airmen believed that there was no direct defense against the bombers and that, in Prime Minister Stanley Baldwin’s words, “the bomber will always get through.” Therefore, the British put their faith and effort into a strategic bomber force, neglecting most defensive air efforts. Not until 1937 did the Royal Air Force (RAF) shift its emphasis from bombers to fighters. On 1 January 1938 the British had only 180 antiaircraft guns larger than 50 mm. This number slowly increased to 341 by September 1938 (Munich), to 540 in September 1939 (declaration of war), and to 1,140 during the Battle of Britain.

During the decisive Battle of Britain, antiaircraft artillery played a secondary role to RAF fighters. The gunners claimed 357 of the 1,733 German aircraft the British believed they destroyed, even though a more recent source puts the gunners’ scores at less than 300. But the measure of efficiency must include more than simply claims. By the end of September 1940, the British estimated that 48 per- cent of the German bombers turned back from the defended areas. Even if that is an overestimation, flak unquestionably forced the bombers higher, unnerved the crews, and resulted in reduced bombing accuracy. In addition, antiaircraft guns were the principal defense weapon against night attacks as night fighters were in their infancy. By the end of 1940 antiaircraft artillery defenses claimed 85 percent of the British night kills.

British antiaircraft artillery defenses had a number of ‘problems, for example, their first kill-three days after the declaration of war-was unfortunately a friendly aircraft that had even given the correct recognition signal. (The first German aircraft claimed by antiaircraft artillery did not come until over a month later, on .19 October 1939.) The defenses consisted of a mixture of older three-inch guns, which the British employed until 1943, and the new 3.7- inch guns . Sighting was visual until October 1940, when the British began to equip their forces with gun-laying radar. Radar made a big difference-the number of rounds fired per claim at night fell from 30,000 in September (when German night bombing began), to 11,000 in October, and to 4,087 in January 1941.

A problem that hampered British antiaircraft defenses throughout the war was that of personnel. The British sent their regular antiaircraft units overseas and relied on territorial forces, similar to the American National Guard, for home defense. At the beginning of the war, the territorial forces were of top quality. But as the war continued, experienced men were reassigned to other duties, and the overall quality of the forces declined. The first group of 25 militiamen to arrive at one battery, after passing through a medical examination at a recruiting center, included two individuals with advanced cases of venereal disease, one person with a withered right arm, one mentally deficient, one with no thumbs, and a sixth whose glass eye fell out when he ran.

The drain on antiaircraft personnel forced the British to take drastic measures-they incorporated women into what they called mixed batteries. The first such unit became operational in August 1941 ; in it women filled all positions except those involving heavy loading and firing. The women served well in many capacities, the principal problems resulting not from them but from their parents, friends, and British culture. In all, about 68,000 women served in British antiaircraft units during the war.

Another approach to the manpower shortage was to use the Home Guard. These men were, for the most part, willing enough but were either over age or physically restricted. In addition, they could only serve 48 hours every 28 days. The peak strength of the Home Guard serving guns exceeded 145,000 in January 1944. One antiaircraft weapon employed by the Home Guard early in October 1941 was the terrifying but ineffective unguided rocket.

In July 1941 the British deployed 1,000 rocket barrels. Almost 6,000 were deployed by July 1943, most of which were twin-barrel devices. But rocket units registered few claims.

Despite these measures to compensate for shortages in man- power, the number of personnel assigned to antiaircraft duties declined from 330,000 in 1941 to 264,000 in mid- 1942. Britain just did not have sufficient personnel for all its needs, and the number of personnel available for anti- aircraft duties determined how many guns the British could operate.

The Germans also faced stiff opposition from Allied antiaircraft artillery on the battlefield. Initially, mobile war- fare and an inadequate number of guns reduced the effectiveness of Allied flak; but after the first few years of the war, especially in static positions, the situation changed to the detriment of the German air force (GAF).

At the siege of Tobruk, for example, the Luftwaffe made a determined effort to silence British antiaircraft guns and shut down the harbor. From April 1941 (when the garrison was cut off) until November 1941 (when it was relieved), British flak units engaged 4,105 aircraft with 28 heavy guns, 18 40-mm Bofors, and 42 captured Italian 20-mm Bredas. The gunners claimed 374 aircraft destroyed, probably destroyed, and damaged. More important, the Ger- mans sank only seven ships during the siege and failed to close the harbor.

In 1941 the vital British defense facilities on Malta came under aerial siege. The island, only 60 miles from Sicily, was critical in the battle for the Mediterranean and North Africa. In early 1942 the German air force won air superiority over Malta and pounded it ferociously. For two months the British antiaircraft gunners defended Malta alone. The critical month was April when Axis airmen flew 10,323 sorties and dropped about 7,000 tons of bombs, about half the total tonnage unloaded on the island. The British claimed 102 aircraft destroyed that month; however, the correct figure is probably closer to 37. During the entire campaign the defenders (airmen and gunners) claimed between 860 and 1,000 aircraft destroyed on 1,199 air raids, while the Axis admit to the loss of 567 . Whatever the actual number, the stout and successful defense of Malta contributed immensely to the Axis defeat in North Africa.

Developments in technology aided the defenders. By 1943 the British converted from powder to mechanical fuzes. Flashless propellants also increased the efficiency of their guns, as did automatic fuze setters that improved ac- curacy and increased the rate of fire two and one-half to three times. By this time, electric predictors were also used.

German bombing attacks on Britain trailed off in 1941, as the Soviet campaign began to dominate the European war. On 27 March 1942 the Germans opened a new phase in the air war against Britain with attacks on southern coastal towns by small numbers of low-flying fighter-bombers. A lack of early warning devices, a wide range of targets, and an inadequate number of light antiaircraft guns created problems for the defenders. The British could do nothing about the first two factors, but they did increase the number of 40-mm guns from 43 in May 1942 to 267 by the end of September. By April 1943 the British had deployed 917 40- mm guns, 424 20-mm guns, and 506 two-pounders (one- third of their available 40 mms and two-fifths of their light flak units) along the southern coast. The increased alertness of the gunners and increased number of guns brought about impressive results. The gunners downed four of 42 sorties on 23 May, four of 24 sorties on 25 May, and 10 of 35 sorties on 30 May. In this phase of the air war-hit-and- run attacks on fringe targets-the British claimed 56 aircraft destroyed of 1,250 sorties, an attrition rate of 4.5 percent.