This paper examines uses of the term “brother” in describing male relationships in memoirs of the First World War and interwar period by Ottoman Army officers from the Mashriq including Taha al-Hashimi, Nuri al-Sa‘id, Jafar al-‘Askari, Fawzi al-Qawuqji, ‘Ali Jawdat, Tahsin ‘Ali, Naji Shawkat, and Tawfiq al-Suwaydi, members of what Michael Provence called “The Last Ottoman Generation.” These relationships comprise a variety of forms, including fictive kinship, kinship through marriage, and siblinghood. Some bonds demonstrate forms of homosociality as theorized by Nils Hammarén and Thomas Johansson, strengthening male relationships in furtherance of either vertical homosociality, preserving patriarchy in ways explored by Ayşe Gül Altınay in the Turkish military, as well as horizontal homosociality, revealing friendship and intimate connection, similar to Mary Ann Fay’s findings regarding use of the term “brother” among 18th century military slaves in Egypt, or Josephine Hoegaerts’ study of fictive kinship and masculinity in the 19th century Belgian Army. Interestingly, some brotherly relationships comprised more than fictive kinship. Officers’ marriages reveal examples of marrying the sister or female extended relative of fellow officers, thereby becoming kin and sometimes brothers-in-law. This is most clearly evident in the case of Nuri al-Sa'id and Jafar al-‘Askari, but is also apparent in the case of ‘Ali Jawdat and the military officer uncle of his bride to be, Nazik ‘Ali Jawdat. Upon initial assessment, these marriages resemble “triangular” relations through which men strengthen male-male relationships through women, but further investigation may illuminate other aspects of courtship and gender expectations of marriage by men, expanding on works by Kate Dannies, Mary Ann Fay, Cem Behar, and Alan Duben. Another important “brother” relationship among officers is siblinghood. Three al-‘Askari brothers, two al-Hashimi brothers, three Shawkat brothers, and two Suwaydi brothers appear as officers in these memoirs. These sibling relationships add another layer to the concept of “brothers” and “brotherhood” that centers the family and familial relationships in the study of Ottoman officer experiences, building on recent pioneering work by Linda Maynard into sibling relationships in First World War Britain. These uses of “brother” in Ottoman officer memoirs reveal the entangled connections of family, masculinity, military training, and conceptions of the nation to shape discourses about male-male relationships. This work also identifies men’s attitudes and expectations toward marriage and establishment of families across late Ottoman and early interwar periods, in addition to the important network of relationships between siblings in the late Ottoman Empire.