“At this moment, I am leaving for Mainz,” Napoleon informed his father-in-law, Kaiser Francis, on 13 April 1813. “I had no plans to do so before the 20th but the news I received of enemy movements on the left bank of the Elbe has prompted me to hasten my departure by several days. I will be at Mainz between the 15th and 16th.” From Mainz, he informed Jerome on the 18th that Marshals Bessières and Marmont had reached Eisenach with “a corps of 50,000 men, all French,” that Ney had arrived at Erfurt with 60,000 men, and that Bertrand had started his march from Bamberg to Coburg “with 60,000 men, two-thirds French, one-third Italian.” According to the latest report Napoleon received from Eugene, dated the 16th, the left wing of Army of the Elbe extended to the Elbe west of its confluence with the Saale while the right reached the foothills of the Harz. Napoleon anxiously sought to push his Army of the Main to the Saale just south of Eugene. His chief of staff, Marshal Louis-Alexandre Berthier, explained to Ney that “this movement requires some caution and, once completed, IV, III, VI Corps, and the Guard will be on the line of the Saale on the same battlefield.”