The OHL, through the Hindenburg Programme, a total war strategy, sought decisive victory. Ludendorff ordered the resumption of the unrestricted U-boat Campaign, which, along with the Zimmermann Telegram, provoked the United States to enter the war. The OHL ensured safe passage for Vladimir Lenin and his associates from Switzerland to Russia. After the October Revolution, the OHL negotiated the Treaty of Brest-Litovsk to free troops for the 1918 German spring offensive on the Western Front. As the tide of the war turned against Germany with the Allied Hundred Days Offensive, in late September 1918, Ludendorff called for the "parliamentisation" of the German government and immediate armistice negotiations. When he reversed course and demanded the fight to be resumed in October, Ludendorff was sacked and replaced by Lieutenant-General Wilhelm Groener. Hindenburg remained in office until his resignation from the armed forces in the summer of 1919.