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Artillery Firing Speed

In 17th century European warfare, it is recorded that artillery might only fire 7 shots per gun in an 8 hour battle. Even in a siege, a gun fired a maximum of only 5 times per day. Why didn't artillery fire more to quickly break forts and devastate enemy soldiers?

Why didn't armies bring more ammunition for artillery to fire more often?

Were they afraid their guns would overheat or break from overuse?

Or was artillery in the 17th century really time consuming to dial in and reposition on a target between each shot?

Why didn't armies want more ammunition to quickly overwhelm enemy troops or forts?

The following is from the book Supplying War, Logistics From Wallenstein to Patton by Crevald:

"…Before drawing our conclusions from these facts, a word must be said about the consumption of ammunition in the wars of the two centuries preceding the French Revolution. That figures on this problem are so very hard to obtain is itself an indication that it was not very important. Compared to the provision of subsistence, that of ammunition was to remain insignificant until well after the Franco-Prussian War of 1870.

Indeed, so small were the quantities required that armies normally took along a single supply for the entire campaign, resupply from base being effected only on comparatively rare occasions - most frequently, of course, during sieges.

In the first half of the seventeenth century, an army going on campaign took along a basic load of 100 balls for each artillery barrel, which is not surprising in view of the fact that, even during a siege, no gun was expected to fire more than five times a day.

Later in the century, Vauban calculated four rounds per gun per day, so that consumption of ammunition remained negligible beside that of food and fodder. The figures for field operations were lower still; during two battles in 1636-1638, the Bavarian artillery only fired seven shots per gun in eight hours, though these figures owe their survival to the fact that they were regarded as a record low.

Frederick II, who relied heavily on his artillery, usually took along 180 balls on campaign, and instances when a shortage of ammunition forced him to alter his plans only occurred during sieges. Apart from this, there is no evidence that the problem of ammunition supply had any influence on the conduct of operations, nor is the issue mentioned…"

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Answer by: ook_the_librarian_ (Natural Philosopher)

I love this because it's about one of my favourite things!

Cannons!

Weight: A single iron cannonball for a medium siege gun, say, a 24-pounder, weighed about... er... 24 pounds, not including powder. Moving just 100 rounds for one gun meant hauling over a ton of shot plus barrels of powder. For a whole siege train of dozens of guns, this became an immense burden on pre-modern supply systems that relied on wagons and draft animals. Remember we haven't hit the age of steam trains in a significant way, although I do believe by now there were such things being built in various places, but that is not what we are talking about.

Prioritization: Armies had to prioritize food and fodder, which consumed far more transport capacity than ammunition. In fact, Creveld emphasizes that subsistence was the overriding constraint in pre-industrial armies, not ammunition. Ammunition was, and should always be according to Sun Tzu, among others, less important than keeping the troops fed. You can't fire much of anything with dead or dying or even starving troops.

Doctrine and Perception: Commanders did not think of artillery as a "consumable firepower asset" in the modern sense. It was a specialized support arm. Infantry and cavalry still decided most battles. Artillery softened positions, disrupted morale, or forced defenders to keep their heads down, but no one expected guns alone to break a fortress quickly. Armies often brought only a fixed campaign load of ammunition. Resupply was considered unusual because, as Creveld notes, the expectation was not to expend ammunition rapidly.

Ok that's cool but WHY were they not used to do the overwhelming fire thing? Surely big bada boom multiplied by a lot is a good thing? It means less men and animals are killed or injured, for one thing. SO bring less men and animals and more artillery!

One of the biggest hurdles was rate of fire and, by extension crew fatigue/death.

Loading and aiming artillery was labor-intensive, slow, and could be your last. Each shot required:

  • Swabbing the barrel to extinguish sparks.
  • Loading powder. 17th-century powder was not chemically stable and varied in quality. Which had a direct effect on gun barrel endurance. Cannons were cast bronze or iron, both prone to cracks. Overheating was less the issue (as with modern rapid-fire weapons) than cumulative stress and/or poor metallurgy. Crews were conservative because losing a gun to an explosion was expensive. Oh, and also deadly.
  • Ramming down the shot. CAREFULLY.
  • Re-aiming, which often meant repositioning the heavy gun. Artillery of the period was very inaccurate compared to 19th–20th century weapons. Each shot nearly always required re-laying the piece because recoil knocked it off aim. The math of ballistics was still rudimentary (before Vauban, Benjamin Robins, and 18th c. improvements).

Even under ideal conditions, large siege guns could only fire about 1–2 times per hour without risking accidents. Over an amount of 8-hour battles, this aligns with the "7 shots per gun" figure we have.

That meant artillery was used more for psychological effect and harassment than for "rapid devastation." In sieges, the emphasis was on deliberate, methodical breaching, not saturation fire. The whole concept of mass firepower to rapidly break the enemy was an 18th–19th century development when both the supply lines and the artillery was strong enough to handle it.

Sources, which were fun to look up because it's been a while since I got to talk about cannons and I got to read a whole bunch of stuff I had forgotten I knew!

Martin van Creveld, Supplying War: Logistics from Wallenstein to Patton (Cambridge University Press, 1977)

Bert S. Hall, Weapons and Warfare in Renaissance Europe: Gunpowder, Technology, and Tactics (Johns Hopkins University Press, 1997)

Jeremy Black, European Warfare, 1494–1660 (Routledge, 2002)

David G. Chandler, The Campaigns of Napoleon (Scribner, 1966)