The battles of Verdun and the Somme resulted in about 2 million casualties on both sides with apparently little to show for it. Were there any voices raised to stop the carnage on either side of the trenches? If so, whose voices and what happened with them?
While not directly answering your question, at least in regards to the Somme, /u/DuxBelisarius covered the Somme campaign in depth (and its goals and achievements) here.