Montgomery initiated his offensive against the Mareth Line on March 20. On April 6, the two Allied armies in Tunisia made contact and formed a single battlefront. Kesselring, immediately after authorizing Rommel to break off the Battle of Kasserine, had sent a telegram to Hitler telling him that the operation had hurt the Americans and parts of the British and French forces so severely that it would take the Allies four to six weeks to recover enough strength for a large-scale offensive. If Rommel had aimed merely to push the Allied troops back from the coastal plain in the east in order to protect his own lines of communication, he was lured into an operation at Kasserine that was hardly worth the effort. Kasserine lengthened the operations in Tunisia, delayed the invasions of Sicily and the Italian mainland, postponed the invasion of southern France, and retarded the decisive events marking the unfolding strategy.