The article deals with the language means of objective modality representation in the texts of the 18th cen. army charters from the archive "Mikhaylovsky stanitsa ataman" (State Archive of Volgograd Region). According to the contextual analysis the meaning of reality is viewed as dominating in the army charters and being explicated with the reality mood (syntactic indicative). The authors point to correlation between the document construction and tense form preferences in the usage: the meaning of reality in the present and past is predominantly presented in the motivation section of the charter, futurum forms are frequently positioned in the administrative part. It is stated that a number of sustained structures that supplant document arrangement functions point to the truth of the facts presented in the paper: they confirm the authenticity of the document, thus verifying the information validity in it. The time point reference is presented with exact dates, event truthfulness is attested by the reference to some other documents. Irreality mood forms associated with the pragmatic modality of volition are also used in the charters. The study revealed some cases of modal meaning convergence, objective and situational types including, the objective modality is conveyed with negative syntactic constrictions. The modality category representation in the construction of army charters studied in the article helps to verify the information function through objectivity and truthfulness that are typical features of official papers.