Field ArTillery - US Army Center Of Military History

a Time Of grOwTh
This French 75-mm. gun, manned by Battery C, 6th Field Artillery, reportedly fired
the first American shot of World War I on 23 October 1917.
measured the azimuth 9 of the target; selected a suitable aiming point, 10 such as a
church steeple, identified on the map; and calculated the azimuth to this object.
The angle between the two lines gave the measurement for setting the sight. The
gunner then rotated the gun until the line of sight was on the aiming point, thus
pointing the muzzle of the gun on the target. Shells would fall within the general
range of the target, the location of which an observer could report back to the gun
battery (Diagram). Employing the same procedures to direct the fire of his guns,
the battery commander either used his aiming circle 11 or had his gunners lay their
sights on a common aiming point. Later, because of technological advances and
improved map-making, an observer was able to call for fire without also having to
see the gun position. Thus, guns could fire from greater distances, farther than the
gunner’s eye could see, and the artillery could operate out of sight of the enemy.
The great difficulty was effective communications between observers and gun
9 Azimuth is the direction expressed as a horizontal clockwise angle measured from north.
10 An aiming point is a sharply defined object that is used as a reference in laying an artillery
piece or for orienting purposes.
11 An aiming circle is an instrument that measures horizontal and vertical angles, used in surveying
and similar work in connection with artillery fire. It is equipped with a magnetic needle so that
magnetic azimuths can also be set off or read.
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