The 138th Personnel Detachment was originally organized and Federally recognized in the Indiana National Guard as HQ Company and HQ Detachment, 38th Division on 7 July 1924 and was reorganized and redesignate two years later as HQ Company, 38th Division. During World War II, it was reorganized and redesignated as HQ and Military Police Company, 38th Infantry division on 1 March 1942; a month later it was again transformed into HQ Company, 38th Infantry Division. It was under this designation that it served in three campaigns in the Asiatic-Pacific Theater, earning an Arrowhead for participating in an assault landing during the invasion of Luzon in the Philippines as well as a Philippine Presidential Unit Citation.
Two more reorganizations awaited the Company—as 38th Administration Company (1959) and 38th Adjutant General Company (1972), both elements of the 38th Infantry Division—before it was relieved from the Division and was expanded, reorganized, and redesignated as the 138th Personnel Services Battalion and the 433rd and 826th Personnel Detachments (the latter two began separate lineages at this point). It did not receive its current designation as the 138th Personnel Detachment until 1 September 2009.
“Honor Pride Service,” the motto of the unit, is displayed in gold text (gold is the color of excellence and achievement) on a black scroll beneath the shield portion of the 138th Personnel Detachment unit crest, officially known as a Distinctive Unit Insignia or DUI. In the center of the seal is the traditional golden-yellow sea lion taken from the seal of the President of the Philippines, which itself is taken from the coat of arms of the city of Manila. It refers to the unit’s World War II service in the Philippines and the Philippine Presidential Unit Citation it was awarded.