How to stop tanks was one of the most controversial issues of World War II.
All nations agreed that a gun was the best method, whether self-propelled,
towed, or mounted on a tank. A brief survey of the antitank doctrine of the
major powers before the war is illuminating. British doctrine was that another
tank was the best way to stop a tank. Other nations relied on the towed antitank
gun, mines, direct fire by artillery, and indirect fire. During the war the self-
propelled tank destroyer was developed, providing a heavier gun than could be
carried by a tank of the same weight.

Although military writers disparaged French prewar doctrine because of its
failure against the Germans in 1940, the French ideas deserve more careful
analysis. They strongly believed that the best defense was the antitank gun.
The French believed that the tank killing zone should be in front of the main
mine of resistance (MLR) and placed the antitank gun line at the forward edge
of the line. Two additional gun lines were located farther back in the MLR.
By dispersing the guns in three lines, all were necessarily weak in view of the
limited number of guns available. ¹ The major fault in the execution of the
doctrine was the poor quality of French antitank guns. The 25mm gun did not
have the power, and a new 47mm gun issued in 1939 was scarce. The French
used the M1897 75mm field gun as an antitank gun, but it had a low initial
muzzle velocity. All three were horse-drawn and too heavy to be easily
manhandled. Once an attack began, the guns could not be moved. ²

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