https://np.reddit.com/r/todayilearned/comments/6g54sq/til_hitler_claimed_to_have_been_spared_by_british/dinq1hy/

Yeah back when wars were fought with battles where both armies lined up in two lines, walked towards each other until they were 30 feet apart and then just shot at each other until one side lost. It still amazes me the honor system was enough for both sides to be like "We'll each form a tight human wall, give each other the easiest possible target and then see how much of each other we can kill." Such a proper way to die in agony.

People generally are keen on 1. winning and 2. not dying. The idea that somehow our current tactical doctrine represents the pinnacle of military achievement and that everyone who came before us were idiots who couldn't comprehend the idea of cover or ambushes is way more popular than even common sense ought to dictate.

Executing solely modern style light infantry tactics with muskets on a Napoleonic era battlefield is a laughably stupid as lining up US Marines in 2003 shoulder to shoulder 40 inches behind the front rank in neat platoons to take Baghdad.

Light infantry tactics were in the musket era useful for rapid ambushes against forces with insufficient calvary, for untrained guerillas who would then turn and run to the wood/hills before they could get closed with and in other situations where mobility was limited by terrain, or in situations where friendly line or cavalry units were near enough to deter a charge. Otherwise, a well disciplined line infantry or cavalry unit would simply face, fire, charge, and cut them down.

People did that shit because it worked better than any other sort of tactics at the time. Around the era of the US civil war, rifling and easier designs and methods for reloading began to mean that you no longer needed 100 guys shooting all at once to have any chance at hitting a distant target, and better firepower and reload times meant that you could stop an advance or charging force with fire alone, instead of bayonets. Not because suddenly all military thinkers stopped being idiots. Though there were certainly people who figured it out earlier and others who didn't figure it out until the early 20th century. Even during the early US civil war, many commanders like "Stonewall" Jackson figured out that rifles meant that the defenders had the upper hand, so he tried figured out ways to bait the union troops to charge into his lines, and was able to defeat larger forces. However, by the end of the US Civil War, almost everyone else had caught on with a few exceptions.

If nearly every single person in the past did something a certain way, it may have not been the best way, but it was probably popular because it worked. Not because they were fucking morons or obsessed with honorable combat .