Herbert York became the first Director of Defense Research and Engineering (DDR&E) in 1958, soon after his ARPA chief-scientist appointment

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Herbert York, having just been named the first chief scientist of the newly created Advanced Research Projects Agency (ARPA) in 1958, became the first Director of Defense Research and Engineering (DDR&E) in the Office of the Secretary of Defense "not long afterward" the same year. Lawrence Livermore's own Science & Technology Review states the sequence directly and separately dates York's move: "York moved to Washington in March 1958, in the middle of the school year, and rented a studio apartment during his first months there." UC San Diego Library's archival finding aid for York's papers confirms he held both posts concurrently from that move: he "left Livermore for Washington, D.C., in 1958 to accept two positions within the Office of the Secretary of Defense: Director of Defense Research and Engineering and the Chief Scientist of the Advanced Research Project's Agency (ARPA, later known as DARPA)." The American Institute of Physics's Niels Bohr Library catalog record for a 1980 oral-history interview with York independently corroborates the DDR&E ordinal: "selection to be the first Director for Defense Research and Engineering (DDR&E)."

DDR&E and ARPA were both products of the same 1958 Department of Defense reorganization that followed Sputnik, but they are distinct offices: ARPA is a funding and research agency, while DDR&E was the senior science-and-technology post inside the Office of the Secretary of Defense itself. York held the ARPA chief-scientist title only briefly before moving into the DDR&E directorship — a third founding-era role alongside his Lawrence Livermore directorship (claim-herbert-york-livermore-director-arpa-cofounder-chief-scientist-1958) that no existing claim-note or entity page in this vault had recorded before this promotion.