On what front were 12 million soldiers killed?

The phrase "12 million soldiers killed" typically refers to the casualties suffered during World War I. This conflict, which lasted from 1914 to 1918, involved numerous fronts, including the Western Front, Eastern Front, and various battles across Europe and beyond. The staggering loss of life was due to the combination of trench warfare, advanced weaponry, and the scale of military mobilization. In total, millions of soldiers and civilians perished during the war, leaving a profound impact on the world.