This series contains materials that shed light upon Oppler's personal and professional life. Included are a photocopy of a book of poems authored by Oppler's father Leo, photographs, and photocopies of his published obituaries. Also included are a handful of materials documenting his daughter Ellen's career as an art historian.
This series consists of unpublished notes and opinions, photographs, and other documents Oppler created or collected while working as head of the Political and Legal Section of the Far Eastern Command. Of note is an autographed photograph of General Lyman L. Lemnitzer.
This series consists of unpublished opinions, memoranda, official documents, photographs, and press summaries that Oppler generated or collected while serving as the International Relations Officer of the United States Forces Japan (USFJ). Of note are Oppler's "Personal Interest File", which contains clippings, USFJ memoranda and reports, and other documents concerning the affairs of Japan, Korea, and the Ryukyu Islands, and his file of clippings and documents concerning the Sunakawa case, which upheld the constitutionality of stationing United States troops in Japan.