Lorraine Campaign and Operation Undertone both occurred during which war?
Operation Undertone Operation Undertone was a large assault by the U.S. Seventh and French 1st Armies of the U.S. Sixth Army Group as part of the Allied invasion of Germany in March 1945 during World War II.
Plan XVII Plan XVII (] ) was the name of a "scheme of mobilization and concentration" that was adopted by the French "Conseil Supérieur de la Guerre" (the peacetime title of the French General Staff) from 1912–1914, to be put into effect by the French Army in the event of war between France and Germany. Though it was not "a prescribed narrative for the campaign" or battle plan, the deployment made possible a prompt invasion of Germany and/or Belgium before Germany could mobilise its reserves, simultaneous to a Russian invasion of East Prussia. The plan was implemented from 7 August 1914, with disastrous consequences for the French, who were defeated in the Battle of the Frontiers (7 August – 13 September) at a cost of 329,000 casualties. The French northern armies were forced into a retreat as far as the Marne river, where in the First Battle of the Marne (5–12 September), the German armies were defeated and forced back to the Aisne river.