 In April 1942 Walker joined the Operations Division ( OPD ) of the War Department General Staff as executive officer of Brigadier General St. Clair Streett 's Theater Group . He co @-@ authored a memorandum with Brigadier General Dwight Eisenhower in which they advanced the position that the determinations of the Joint Chiefs of Staff " must be taken as authoritative unless and until modified by the same or higher authority . " After his death , Walker was awarded the Legion of Merit in recognition of his contributions as a staff officer at OPD . 
