But one phrase stands out, as it always does in ww1 battles. Those brave lads were made by their Officers, to WALK.
I can accept an argument for the massed charges against enemy trenches, but to make them walk? That was not a valid tactic, that was organised slaughter by your own side. That was Generals so out of touch and date with the realities of modern warfare, they were using essentially, Napoleonic era foot soldier tactics in a war that deployed 20th century mechanised warfare, albeit in a more primitive form.
This is a bit of a myth - actually some battalions decided to run, others walked. But there was reason for walking and it probably would have depended on the bit of no-mans land that they had to traverse. The reason was a great many of the waves of assault were hauling large amounts of stuff on their backs, everything they thought they would need when they got there - so running a long distance over lumpy terrain with an extra 50kg, or whatever, on your back (on top of your standard kit btw) would have likely exhausted everyone and if there were Germans to fight at the other end, you don't want to be needing a breather. (In fact this was a common feature of battles throughout the ages - unless you had a horse or a chariot, or were wearing practically nothing, then charges that got to sprint or running speed involving heavily armoured men on foot would only occur when you got very close to the enemy. It was why the bow and especially the horse+bow was such a devastating weapon system against massed ranks of spearmen/hoplites)
My guess is (and I don't have any evidence for this assertion, other than commonsense) is that if the German lines were relatively close, then I suspect running towards the lines would probably have been allowed as the impact of a short 'dash' would have been less tiring (and I
do know running did take place.)
Of course in theory the vast artillery barrages were supposed to clear out the first lines of Germans, remove all the barbed wire etc..., so they were told there would only be a few dazed survivors, hence walking was deemed acceptable. With hindsight of course this was total bunk, although how could one tell until they tried it?
Another reason is, especially for the battles of 1916 - starting with the Somme, the British Conscript Army was very inexperienced and there just wasn't enough time to train them properly (and I mean both officers and men - chain of command and communications was probably one of the biggest failings in the Somme) as the French were screaming for pressure to be taken off Verdun. To coordinate safer and more devastating attacks (such as slipping into no mans land at night
during the barrage and waiting much closer to the German front lines, or to do a walking barrage) required experience and discipline that the British Army had no time to give these men. So they put their faith in a plan with the 'big guns' hoping that they'd smash the enemy and this would protect their green troops.