In Wilson’s War, historian Jim Powell recounts:
By the end of 1917, Western Europe had been embroiled in war for three years, but it was deadlocked. The United States was still on the sidelines.
All (Allied Powers) had suffered horrendous losses. Neither side was able to achieve decisive victory and dictate surrender terms to the other.
Russia was disintegrating and more and more Russians wanted to get out of the war. A settlement with Russia would enable Germany to move soldiers from the Eastern Front to the west- though Germany would still have to keep about a million soldiers in the east as an occupying force.
As historian David Kennedy explained. “The machine hugely amplified the firepower of stationary forces and thereby conferred nearly insuperable advantages on the defense. Its withering fire consumed attacking troops wholesale, forcing the fighting on the Western Front into a grisly deadlock. In the face of such awesome implements of slaughter, 10 million men perished; another 20 million were maimed.”