Final answer:
The Second Battle of the Marne was a decisive Allied victory and a major turning point in World War I. It saw the German forces launching an offensive but ultimately being repelled by the Allies. The battle marked the beginning of the German retreat and their eventual defeat.
Step-by-step explanation:
The Second Battle of the Marne took place in July 1918 during World War I. It was a decisive Allied victory that marked a major turning point in the war. The battle saw the German forces launching a major offensive in an attempt to break through the Allies' lines, but they were ultimately repelled by a combined force of French, British, and American troops. The battle ended with the Allies launching a successful counteroffensive, pushing the Germans back and starting their retreat that would eventually lead to their defeat in the war.