The insignia was a simpler version of the Iron Cross ( the straight-armed so-called Balkenkreuz or beamed cross ) that had been used as an aircraft and tank marking in late World War I. The existence of the Wehrmacht was officially announced on October 15 , 1935 . The insignia was a simpler version of the Iron Cross ( the straight-armed so-called Balkenkreuz or beamed cross ) that had been used as an aircraft and tank marking in late World War I. The existence of the Wehrmacht was officially announced on 15 October 1935 .