Senator Tower maintained a strong interest in defense matters throughout his Senate career, serving on the Joint Committee on Defense Production (1963-1977) and the Senate Armed Services Committee (1965-1985). He was chair of the latter from November 1980 until his retirement from the Senate in early 1985. Official committee materials remain in Washington, D.C., as part of the record of the committee; consequently Armed Services Committee materials are limited and most are copies. Defense related materials were found scattered throughout the collection in boxes labeled "Military/Defense," "Defense Legislation," "Armed Services Committee," "Vietnam," and "Texas Military Bases." Since it was often impossible to establish which of the papers were Armed Services Committee files, defense related papers were pulled into one general subseries.

Materials in the General subseries include correspondence, reports, legislative bills, statements and speeches, talking points, press releases, background materials and briefing books, memoranda, notes and clippings. Many of the files reflect the work of various aides on subjects such as the 1962 controversy over the TFX fighter plane, 1968 legislation (S.3092) concerning foreign military sales, and an electronic low frequency transmission system called Project Sanguine. Materials related to the Strategic Arms Limitation Talks (SALT II), 1978-1979, some of which were generated by the Senate Republican Policy Committee, make up a considerable portion of these papers and include memoranda, statements, clippings, briefing books, and reports. Among the 1981-1984 papers are four folders of copies of incoming correspondence that Senator Tower received as chair of the Senate Armed Services Committee and three folders of an aide's notes and talking points.

The small subseries concerning military bases in Texas contains correspondence, briefing packets, memoranda, press releases and clippings. Among the concerns are base closings, reductions or expansions; contracts that will have an impact on particular Texas bases, and construction proposals. The Vietnam files primarily contain items related to five trips that Senator Tower made to Vietnam and other countries in East Asia. Materials include correspondence, press releases, statements, speeches, writings, transcripts, travel schedules, briefing materials, memoranda, notes, "name lists" of persons (frequently soldiers) to see, clippings, examples of North Vietnamese propaganda, photographs, legislative bills, reports, studies, maps, pamphlets and other materials. Examples of correspondence include letters to and from parents of service personnel whom the senator visited on his trips, letters of introduction (including several from Anna Chennault), letters of thanks to base commanders, and correspondence seeking approval for his trips. Papers such as legislative bills press releases, statements and writings reveal Tower's consistent support for waging a strong war. Included among the writings is a heavily edited draft of a paper entitled "Vietnam: Gradualism or Victory?"