World War I and the line of battle.

So now there are rifles that have yet more range, more accuracy, and an even higher rate of fire then ever before. In fact, there are now machine guns that spit death like nobody's business. With the artillery, the apotheosis of Big Bertha has arrived. And cavalry? In No Man's Land? Fuggettaboutit! Wellington's little trick of having his infantry stay behind little slopes until needed will come to its apotheosis in the infantry trench. The line of battle is going to become the miles long trench line going from Switzerland to the northern French coast.

And yet the generals are still reading Napoleon and still being impressed by "The strength of an army, like the power in mechanics, is estimated by multiplying the mass by the rapidity." They will be very slow to realize that the mass part of the equation has been canceled by machine guns and larger, more accurate artillery. The "rapidity" has been canceled by barbed wire and the craters made by the artillery.

And in fact, one stupid Napoleonic thing they will continue to do is precede infantry charges with massive artillery barrages. Only these barrages will go on for days at a time. Since the line of battle is now in trenches and bunkers, the barrage will do little but make pesky craters and signal to the enemy ahead of time that an infantry charge is coming and that reserves should be moved up. The "poor bloody infantry" is going to shoveled into a harvest of death that has never been seen before.

After WW I, a Capt. B. H. Liddell Hart - a participant in the business end - will come out with a book appropriately entitled "Strategy: the indirect approach" (Ah yes! The indirect approach!) In that book, he will have statistics that show that the average British commander in the late war was just a little too old to be doing what he did for a living.