was in the past a pet fire problem. The effect of frontal fire on artillery whose guns are protected by shields is so small that the expenditure of ammunition is not justifiable.[320] The gap between the steel shields of the French field gun is not large enough to exert a noticeable influence. Steel shields, 3 mm. thick, afford protection against steel jacketed bullets fired at or beyond 300 m.; against “S” and “D” projectiles they afford protection, it is said, beyond 500 m. only. Machine guns directing continuous fire on a point may obtain better results. According to firing tests 3 mm. armor plate can be pierced up to 1000 m. only by special projectiles (solid steel projectiles and those having a steel core), the adoption of which is precluded on practical grounds (variations in sectional density, and difficulty of manufacture).[321] For this reason, it is better to leave the task of destroying shielded batteries, even when they are in the open, to one’s own artillery, than to attack them with infantry. The fire effect of the infantry is not noticeably increased when delivered obliquely against the front of the battery. (Par. 184 German I. D. R.). In Germany the gun commander and cannoneer No. 3, who is posted at the trail, are then especially endangered; but in order to flank the guns effectively and to reach in rear of the shields with its fire, the infantry must move to a flank a distance at least equal to ¹⁄₃ of the range, and even then the fire effect is very small. The effect may even be entirely nullified when the flanking fire is delivered from the side on which the caisson bodies are posted. In this case it suffices to push forward the caisson body to protect the personnel. It is a good plan for infantry to direct its fire on the limbers and the reserve. And again, infantry should not let any opportunity pass to fire on artillery in motion or in the act of limbering or unlimbering within effective range. Guns moved by hand into positions from which direct laying can be employed for the purpose of warding off the infantry attack, offer particularly favorable targets. Infantry that is to capture artillery must approach its objective by means of irregular rushes made by small groups, and increase its fire to the utmost intensity when the limbers are brought up to the guns. The effect of artillery fire is small under 200 m., in the absence of canister.[322] [320] Even prior to the adoption of shields it was demonstrated that infantry was unable to destroy the matériel of batteries so as to render them immobile; it could only interfere with the _personnel_, but could not demolish the batteries. [321] _Mitteilungen über Gegenstände des Artillerie und Geniewesens_, 1907, No. 5. [322] The capture of the Smolenski Artillery Battalion on October 14th, 1904 (Shaho). _Artilleristische Monatshefte_ for March, 1908. [Illustration: Germany. Field Howitzer. Field Gun.] [Illustration: France.]