One other thing to ponder is that the definition of "legal" can vary quite a bit over time.
"Legal" can sometimes be a very flexible concept, subject to change and defined at will by those empowered to do so.
One might also consider lawful vs stupid. 60,000 casualties in a single day might give one cause to question.
One of the two great slaughterhouse battles of World War I, the Somme still rings in the minds of the British as an example of the senseless slaughters of the war. Planned in 1916, the goal of the battle was to be a massive Anglo-French effort to create a rupture in the German lines that could be exploited with a decisive blow. The German attack on Verdun, however, forced the Allied commanders to change their plans, and the battle became a primarily British offensive, though the French still contributed significantly. The British prepared for the offensive with a massive several day artillery barrage on the German lines, which they hoped would damage the German defenses enough to allow British forces to break through. On the opening day of the battle, they learned that it in fact failed to do so when the British suffered 60,000 casualties in one day; the greatest single day loss of life in the history of the British Army. Attacks continued all along the Somme area until 13 November, 1916 when the offensive finally petered out. The battle, though ultimately indecisive as there was no breakthrough, was strategically important to the allies, as it forced the Germans to withdraw 40 miles and later set the stage for the final Allied victory in 1918. The Allies paid for it dearly, however; the Allies lost a total of 623,906 casualties, including 100 tanks and 782 aircraft. The Germans lost nearly 600,000 men.
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