Why was WW 1 such a tragedy for both side? What were the military strategies & tactics employed during ww1?

WW1 was a brutal war. Millions of people died. The tactics of trench warfare was especially horrific. As in All Quiet on the Western Front, each side dug trenches in the dirt. At varying times they would charge the other side. The men charging would get mowed down by gun fire. The hope was that eventually your side would make it to the enemy trench, kill everyone, and claim that piece of land. It sounds pretty ridiculous. With the advent of modern weaponry (machine gun) one's chances of surviving a charge was pretty small. If a soldier was lucky he might return home missing an arm or a leg or some other important appendage. I'm going to attach a link in the source-link below that has a chart on the horrific numbers involved.