Military and diplomatic collections are another strength of the Manuscript Division. Included are the papers of hundreds of career military officers, volunteers, and enlisted personnel as well as defense secretaries, war correspondents, and private citizens caught in the path of war. Joining these military collections are the papers of more than three hundred diplomats and more than half of the individuals who have served as secretary of state. Most of these collections relate to men, which is not surprising, given women's relatively late admittance to the military and diplomatic ranks. Nevertheless these sources, like the division's presidential, congressional, and legal holdings, contain information of interest to those researching the history of women in this country.

Material abounds about women's role in managing households, farms, and businesses when their husbands and fathers left to fight in wars or assume overseas diplomatic posts. Sometimes wives accompanied their husbands to frontier outposts and to overseas embassies and consulates, becoming by extension unofficial representatives of the United States government. By World War I, women were being officially recruited for war work, but before that time, they had worked as army cooks, seamstresses, and laundresses, engaged in espionage, nursed the sick and wounded, and supported the military effort in various other ways, sometimes even going so far as to disguise themselves as men to go into combat. A quick survey of the division's military and diplomatic collections suggests the wealth of information waiting to be mined by women's historians who have not always examined these sources with the same interest and enthusiasm as other collections.