With the tremendous strides in development of combat aviation during the period between World War I and World War II, it became increasingly evident that a corresponding development of AA materiel and tactics was quite necessary. Although the Germans were limited in their military establishment as a result of World War I, they nevertheless conducted extensive research and tests to develop new AA materiel. During this post-war period, also, came experiments with mechanized armored vehicles, and new doctrine as to the possibilities of their employment. Under the circumstances, it was only logical that some experimentation should take place with the object of designing a gun which could be used against either aircraft or mechanized ground vehicles. In 1936 the Spanish Civil War gave the Germans a chance to test their first efforts along these lines; in 1939 the campaign in Poland permitted a full test of the refined product, and results were used as a guide on which to base standardization and further development. The later campaign in France and other campaigns have, of course, served as further proving grounds.

b. Mobility

One of the main results of the battle experiences of the Germans has been vindication of the concept that AA guns used in any but purely static positions must be highly mobile, and that even in static situations it is to the best interests of protection against hostile aircraft to have a certain proportion of the AA artillery defenses in a highly mobile state for purposes of flexibility. Furthermore, the increased use of AA weapons with mobile units in the field has given a great spur to development of AA mobility.

c. Dual-Purpose Construction

With the practical tests of 1936 in the Spanish Civil War came the realization that with some modifications the then current AA weapons would have definite possibilities as effective antitank weapons. This finding was the more acceptable in view of the German military precept of acting on the offense wherever possible. The possibility of employing AA guns in forward areas in an offensive role definitely removed them from the status of defensive weapons and placed them in the category of important offensive weapons. The Polish Campaign, the French Campaign, and the early successes of Rommel in the Libyan Desert are eloquent proofs of the increasing development and use of AA weapons against mechanized ground targets. It should be remembered, of course, that AA gunnery demands weapons with a high rate of fire, rapid fire-control calculation, fast tracking speeds, and a high muzzle velocity. These factors contributed materially in the decision to adapt these weapons to an AT role. The original difficulty in making these AA weapons dual-purpose rested mainly in securing a satisfactory mobile carriage or mount which could withstand equally well the shock and recoil of high-elevation AA fire, and of horizontal and subhorizontal fire.

d. Multipurpose Use

With satisfactory development and use of the AA gun as an AT weapon came the logical discovery that the main AA/AT weapons could be used against targets other than aircraft or tanks. Thus we hear of the 88-mm guns being used against fortified gun positions, as well as for the direct support of ground troops, for interdiction fire against enemy communications, and for fire against river and coastal targets. We even hear of its being mounted on U-boats. As a result of these and similar experiences, German field commanders have found AA artillery to be one of their most useful weapons, and there is evidence of a trend suggesting that German artillery of the future, up to a certain caliber, will include an even greater proportion of AA weapons placed on multipurpose mounts.

e. German Classification of Flak Weapons

Although Flak weapons are generally referred to by the United Nations as light Flak and heavy Flak, probably because of the classification of AA Abteilungen into heavy (mixed) and light units, the Germans divide their Flak guns into the three general classifications: light, medium, and heavy. Light guns include only the various types of 20-mm Flak weapons; medium guns include the 37-mm, 40-mm, 47-mm, and reported 50-mm Flak weapons; and heavy Flak consists of the 75-mm, 88-mm, 105-mm, 127-mm, and 150-mm weapons. Of these guns, only the 20-mm, 37-mm, 88-mm, 105-mm, and 150-mm are used by the Germans to any great extent.