The Robert Johnston papers (36 items) consist of letters from November 1863 to April 1865, during Johnston’s time with the Confederate Army; they track his movements around Virginia and Tennessee. The letters were primarily written to his wife Catherine "Kate" S. Johnston (also addressed "Mrs. C.S. Johnston" and "Mrs. Robert Johnston") who lived in Albany, New York, with her father, the retired General John Van Rensselaer.
Johnston's letters often concern his request for news about his young children. He often discussed friends and family members, but mentioned little of military matters, aside from officers with whom he has become friends. His letter of November 24, 1863, noted a recent bout of influenza in the camp and on March 30, 1864, Johnston wrote of being offered a professor's chair. In letters he wrote immediately following major battles, he does not mention them at length. However, some of their letters seem to have gotten lost in the mail, as he sadly noted. In his letter of April 8, 1865, he gave Kate explicit directions on how to address a letter to him and about what the appropriate length should be. The letter of February 20, 1865, contained a message from an unnamed examiner, who noted that the letter was too long and that it was supposed to be only one page in length.
Later letters have interesting content pertaining to the capture of Petersburg and Richmond and the end of the war. In his letter of April 4, 1865, Johnston mentioned his desire to see his mother and sister before the imminent evacuation of Petersburg, and that he had surrendered to Union General [George Henry?] Thomas of the Union and had received parole. Likewise, in his letter of the April 12, 1865, he expressed uncertainty about his legal position following the surrender of General Lee at Appomattox.