Answer:
He was afraid of fighting a war on two fronts.
Explanation:
He had seen the disastrous effects of fighting on two fronts in WWI, which he served in. Though the Central Powers won considerable concession in the Treaty of Brest-Litovsk, they did not move those troops to the western front. Instead, they continued to station troops in the east, in an attempt to solidify their gains. The western front collapsed under joint Entente pressure, thus forcing Germany to sue for peace.
