This is coolbert.
Here from a web site dedicated to World War One [WW1] history, an extract with my comments regarding the British seven day artillery bombardment prior to the grand offensive on the Somme, 1916:
"A Slow Fuse - Hitler's World War One Experience"
"One of the battle's [Somme] greatest myths claims that the Kaiser's soldiers were hunkered down in bunkers impervious to the Allied bombardment - and that is how the British saw it. Believing the enemy had been annihilated, they were shocked to find that the Germans had not only survived but were able to resist the attacks. 'Shellproof' bunkers became the only possible explanation for this."
"While it is true that the Germans were in well built defences, it is just as true that the heaviest of British shells could obliterate pretty much anything in their path - including most bunkers. The Germans were subjected to one of the world's heaviest bombardments. It is impossible to know just how many dug-outs became tombs. The noise alone put fear of God into the soldiers and this was combined with the knowledge that an incoming shell could bring instant death; no wonder many men were driven out of their minds."
"It became a question of mental toughness. If enough men remained alive and sane, then the trenches could be held and re-enforcements brought up to face the onslaught. The tactic, as the British found out, worked."
With regard to shell-proof bunkers and [one of the] the "greatest myths" of the battle, the ability of the German infantry to survive the intense, hitherto unsurpassed, and seemingly all-powerful and devastating artillery bombardment, the comments of John Keegan from his book, "The Face of Battle" are most germane:
"During the afternoon [of 26 June] aerial torpedoes, fired from heavy mortars [super-heavy howitzers] in the British front-line, made their first appearance. Coming down almost perpendicularly from a great height, these monsters bored deep into the ground and then burst . . . The Germans, who up till now had endured the inferno almost with indifference, began to feel alarmed. Every nerve was strained as they sat listening to the devilish noise and waited for the dull thud of the next torpedo as it buried itself in the ground and then the devastating explosion . . . in spite of the devastation and chaos on the surface the defenders in those of the deep dug-outs still intact (the majority) had . . . survived the ordeal. For seven days and night they had sat on the long wooden benches and or on the wire beds in the evil-smelling dug-outs some twenty feet and more below ground. The incessant noise and the need for constant watchfulness had allowed them little sleep, and ever-present, too, had been the fear that their dug-outs might at any time become living tomb."
"But they were alive"!!
The Germans WERE VERY SECURE in their "mined" dugouts. Thirty or so feet deep [10 meters], perhaps even designed by mining engineers and dug by professional miners that also happened to be front line troops!
[the Japanese fortifications and tunnel complexes at Iwo Jima, World War Two [WW2] were very similar in nature!!]
What was required for British success in annihilating those deep-underground dugouts of the Germans was heavy artillery firing with pinpoint accuracy BURROWING rounds with delayed fusing.
Artillery pieces of 8 inch or greater bore, preferably howitzers lobbing a round on a high trajectory, the shell descending downward almost vertically, impacting close to the German dugout, "burrowing" and then exploding.
[the British had on the battlefield 6-, 8-, 9.2-, 12-, and 15 inch howitzers [155 mm, 203 mm, 234 mm, 304 mm, 381 mm respectively]. Only the latter two had the capability to destroy a mined dug-out. Of the 15 inch howitzer there existed six of those, and with a carefully rationed number of shells to be fired!]
Some of the statistics as cited by Keegan give an indication of WHY the British bombardment was so ineffective:
* Of the 1.5 million artillery rounds fired during the seven day bombardment at the Somme, two-thirds [1 million] were fired from 18 pounder artillery pieces. NOT burrowing grounds but air-burst or ground-impact fuse, detonating a SHRAPNEL round! These were for wire cutting. totally 100 % ineffective in destroying the deep dugouts.
* Of the remaining 0.5 million artillery rounds fired, only a small fraction of those were of the big-bore, deep-burrowing variety that were needed.
* Those British artilleryman manning those pieces that had the capability to obliterate the German dugouts with a single direct-hit round DID NOT KNOW WITH PRECISION THE LOCATION OF THE DUG-OUTS OR ENTRANCES OF SAME AND ALSO WERE NOT SKILLED ENOUGH TO OPERATE AND AIM THEIR PIECES WITH THE ACCURACY REQUIRED EVEN IF THEY DID KNOW THE PRECISE LOCATIONS OF THE DUG-OUTS!!
The ability of the German to survive the bombardment was in part due to mental toughness, the British using "the wrong sort of projectile for the job", and that the British gunners "lacked the skill to put a shell where they wanted it to fall" [often not knowing exactly where to put the shell in the first place!!]!
IF ONLY A MAJORITY OF THE MACHINE GUNNERS IN THOSE MINED DUG-OUTS SURVIVED [A MAJORITY IN FACT SURVIVING], THAT WAS ALL NEED TO DEFEAT THE BRITISH GROUND ASSAULT OF JULY 1!!
This - - of course - - to the chagrin of the attacking British - - is exactly what occurred at the Somme!