“...that it took time for generals to unlearn the lessons learned as young officers.”
Or, the general (Kitchner) did not care much about the carnage, as in WWI, when 20,000 British soldiers were killed in one morning.
I saw an old, old WWI German machine gunner interviewed about the battle. He broke down sobbing and said he quit firing his machine gun because he got sick from killing so many British soldiers.
Kitchener, Haig... Shoulda been hanged. That fool Haig still liked cavalry charges and thought them a viable tactic until the day he died. Which wasn’t soon enough.