The German military command put the Schlieffen Plan into action at the start of the war, the basis of the plan was to bring a swift defeat to the french by attacking through Belgium and quickly taking the french industrial region and capital. The major point was to focus all power onto the western front and leave the eastern front with the bare minimum. the plan eventually became unsuccessful after the defeat caused by the french at the first battle of Marne. The defeat caused Germany to have to stop its assault, buying time for the east to collapse on the thin German lines.
