In ballistics, the elevation is the angle between the horizontal plane
and the direction of the barrel of a gun, mortar or heavy artillery.
Originally, elevation was a linear measure of how high the gunners had
to physically lift the muzzle of a gun up from the gun carriage to hit
targets at a certain distance.
1 Pre-WWI and WWI
2 WWII and beyond
3 See also
Pre-WWI and WWI
Though early 20th-century firearms were relatively easy to fire,
artillery was not. Before and during World War I, the only way to
effectively fire artillery was plotting points on a plane.
Most artillery units seldom employed their cannons in small numbers.
Instead of using pin-point artillery firing they used old means of
"fire for effect" using artillery en masse. This tactic was employed
successfully by past armies.
But changes have been made since past wars and in World War I,
artillery was more accurate than before, although not as accurate as
artillery one century newer. The tactics of artillery from previous
wars were carried on, and still had similar success.
battleships also carried large caliber guns that needed to be elevated
to certain degrees to accurately hit targets, and they also had the
similar drawbacks of land artillery.
WWII and beyond
As time passed on, more accurate artillery guns were made, and they
came in different varieties. Small artillery pieces were used as
mortars, medium sized artillery guns became tank guns, and the largest
artillery guns became long range land batteries and battleship
With the introduction of better tanks in World War II, elevation was
once again a problem for tank gunners, which had to aim through the
Gunner's Auxiliary Sights (GAS) or even through iron sights. Though
the problem was not that evident as tanks fired rounds at a higher
velocity than normal artillery, making aiming less of a hassle.
As with World War I,
World War II
World War II artillery was almost like its old
counterpart. But in the war came the introduction of the FCS or the
fire-control system, which made firing artillery accurately easier.
With the advancements in the 21st century, it has become easy to
determine how much elevation a gun needed to hit a target. The laser
rangefinder is a component of FCS, and can accurately determine the
range of the target, thereby calculating how much elevation the gun
needs, making today's guns highly accurate.
Gunnery Instructions, U.S. Navy (1913), Register No. 4090 
Gunnery And Explosives For
Artillery Officers (1911) 
Fire Control Fundamentals, NAVPERS 91900 (1953), Part C: The
Projectile in Flight - Exterior
FM 6-40, Tactics, Techniques, and Procedures for Field Artillery
Manual Cannon Gunnery (23 April 1996), Chapter 3 - Ballistics; Marine
Corps Warfighting Publication No. 3-1.6.19 
FM 23-91, Mortar Gunnery (1 March 2000), Chapter 2 Fundamentals of
Mortar Gunnery 
Fundamentals of Naval Weapons Systems: Chapter 19 (Weapons and Systems
Engineering Department United States Naval Academy) 
Naval Ordnance and Gunnery (Vol.1 - Naval Ordnance) NAVPERS 10797-A
Naval Ordnance and Gunnery (Vol.2 - Fire Control) NAVPERS 10798-A