In terms of shells per-minute, per-square mile. What was the most concentrated artillery bombardment in history? Not the largest in total (which was, IIRC D-day) but the largest bombardment, in the shortest time, on the smallest patch of land.
My guess would be the pacific island campaigns during WW2 (some of which were fought over very small areas, with lots of heavy weapons).
Probably not what you’re looking for because it wasn’t geographically concentrated but in a memorable phrase I recall one historian describing the massed artillery preparation for the final assault on Germany from the Soviets as utilising ‘atomic level firepower’ in terms of tonnage of shells being delivered in a short space of time, albeit over an entire front.
The Soviets were very fond of artillery though so it may have been something on the Eastern front but I don’t know enough about the campaign to say.
Wiki says over 40,000 guns and 3,000 Katyusha trucks.
Battle of the Somme in WWI is a good contender although there were several epic sized artillery barrages in that war (e.g. Battle of Verdun). Supposedly 1,700,000 artillery shells were fired over the course of a week pretty much non-stop.
That is:
…nonstop for a week.
Verdun was likewise massive in scope. Here is a picture taken a few years ago of Verdun…the shell holes are still clearly visible even 100 years later.
Here is a recent picture of part of the battlefield of the Somme. You can still see shell pockmarks and trenches.
You’re going to run into issues with a clear answer. A “Battalion 1, time on target” mission will beat any of the big named missions if they all target the same grid coordinates. That’s every tube in the battalion dropping a round near simultaneously on the same aiming point ± 50 meters. For density of fire it’s hard to beat that.
More modern use of improved conventional munitions (aka bomblets) can make accounting hard. How does one MLRS rocket with count? Each rocket contained 644 submuntions. Just look at the description of a possible mission from wiki:
That’s less than 40 seconds targeting an area about 1km square. If each bomblet counts the density of fire is pretty extreme. There’s a reason it’s been jokingly called the “Grid Square Removal System.” It saw plenty of use in counterbattery fires against Iraqi Artillery during the first Gulf War…frequently with the mission starting before the Iraqi rounds had even landed.
Some of the most modern SP artillery pieces complicate things too. By varying charges and angles automatically each gun can potentially deliver all it’s rounds in a time on target fashion. I don’t know if any of them have actually been used in say a battery or battalion time on target, with each tube firing TOT, yet. The potential to greatly exceed anything that’s come before is certainly there though.
As technology has improved it’s gotten to be more of a matter of how dense do we want to make the fires not how dense can we make them.
Upshot-Knothole Grable is disqualified on several levels, right?
(A live fire bombardment from an M65 battalion would have been breathtaking…three batteries of two guns each, with a 15kt yield. So, 90 kt a volley from the battalion, or with the reported firing rate, just over one megaton per hour.)
(Assuming no counter-battery attacks.)
(Which would be silly.)
Silly is good. 
Dan Carlin, in his “Hardcore History” podcast, gives WWI a 10 to 15-hour treatment over five or six episodes and man, is it an epic account.
Anyway, his recital of several eyewitness accounts of the battles mentioned above (Verdun, the Somme) paint nothing less than an apocalyptic hellscape.
He recalls stands of full-sized trees blown sky-high and then, as they are falling and before they can land, returned to the air by additional blast after blast. Just crazy.
A phenomenal podcast series on that woeful, pointless war. Check it out!
I am afraid poor old Atomic Annie will have to sit quietly out at FT Sill with no glory for the old girl.
Over thirty years later and I still remember this cover from the old British comic ‘Battle’
http://static5.comicvine.com/uploads/scale_large/12/124613/3173469-battle+354+pagecover.jpg
And that was a comic for children (I had to sneak read them as they were bought for my brother) they sure didn’t mess around back then.
Ah I see, thank you 
For some reason 3/second doesn’t seem all that “epic”. So, to give myself an idea, I found an online metronome. Go to the link below and set the slider to 169 (bpm or beats per minute) and hit the play button.
Now imagine each of those beats is an artillery shell exploding and it runs non-stop for a week.
Believe the Somme it is when scored for intensity, duration , contiguous area and overall daisy cutting (bomb idiom for levelling everything )
WW-II russian fightback was done with accuracy and blietzkreig fashion…It was only softening the line up for an advance. At the Somme, they just fireed down the line continuously and effectively contiguously (not literally all at once, but the aiming to do so in short time frames.)
Soviet offensive to knock Finland out of WWII had a really heavy concentration of artillery at the breakthrough sector - over 200 pieces per 1 km of front. I’ve always heard it is one of the most intense concentrations of artillery firepower in WWII. The survivors called it “the Steel Storm of Kannas”.
I think that’s the operation with the quote :
“Gentlemen, we may not change history, but we will certainly change geography”
The battle of seelow heights (part of the battle of Berlin) saw the Soviets concentrate 9000 artillery guns on a 18.5 mile front. Up to half a million shells in the first 30 minutes…
It is estimated that the ordnance delivered in Somme over 4 days would have been delivered in 90 minutes here…
The Soviet army called artillery “the god of war”
The bombardment at Second El Amein was pretty intense.
I’ve heard that at one of the battlefields, Somme or Verdun, forty million shells were fired in all. Even over a year, that’s just… inconceivable. A hundred thousand shells a day. And for so little gain.
Yeah…and it’s not just the sheer firepower of it all. Consider the logistics.
Manufacturing that much, that fast, is remarkable for the era but even more remarkable is when you consider that trucks were barely a thing back then. Most deliveries were by horse drawn wagons. I’d be surprised if those wagons could carry more than a few dozen shells at a time (of course shells came in lots of sizes from not too big to very big). Even with modern trucks it would be quite a feat. (Sure it would be by ship and rail for a lot of it but the “last mile” is always going to be a truck or horse drawn wagon.)
There was, in fact, a Shell Crisis in 1915, which was a major political scandal in the UK, caused partially by the fact the Western Front had stabilized to the extent that large-scale shell movement was possible, and partially by a shift in doctrine encouraging shelling field fortifications (requiring high explosives) instead of shelling infantry (requiring low explosives and shrapnel). So the use of large-scale bombardments as a military tactic, particularly bombardments involving a lot of heavy high-explosive rounds, had a hand in what we now consider the industrial aspects of total war.
http://encyclopedia.1914-1918-online.net/article/shells_crisis_of_1915
Charley’s War is unrelentingly bleak and grim. I’ve a few volumes of the collected strips, and yeah, it’s strong stuff for a children’s comic. Highly recommended though.
Furthermore, people still die every year from those fucking shells. There’s a swath of land that is still simply unfit for cultivation or habitation, because there’s too much shit ready to blow just underneath the topsoil, not to mention arsenic & mustard gas.
It’s a rare battle that kills the country on top of the men.
