<prompt> Translate the following text to EnglishSheria ya 1947 ya kuanzisha DOD ilibadilishwa zaidi na Bunge katika 1949, 1953, 1958, na 1986 ili kuboresha ufanisi wa muundo wa idara.  <response>: It is instructive to note that the 1947 legislation creating DOD was further changed by the Congress in 1949, 1953, 1958, and 1986 in order to improve the departments structural effectiveness. 