With the thesis defence held on 27 March 2013, Željko Heimer accquired his doctorate at the post-graduate study of sociology at the Faculty of Humanities and Social Studies of the University of Zagreb. The thesis titled »Croatian Armed Forces Identity as Expressed through the Military Unit Flags in the Homeland War and Following it« was made under the mentorship of Prof. Ozren Žunec, the Chair of Military Sociology. Besides the mentor, the commission for the thesis defence was composed by Prof. Ognjen Čaldarović, as the commission chiarman, and Prof. Nikša Stančić.
The thesis studies the military unit flags as symbols of group identity and vexillology as an interdisciplinary area of study of flags and their use. The goals of the work were to show that sociology has a central place in vexillology, but also that sociology may not express some aspects of social reality without researching flags. Also, the goals included provision of a theoretical frame for evxillology as an interdisciplinary field of science and use of such frame on the flags of military units of the Croatian Armed Forces (CAF). The concepts of identity, military, symbols, science and the Homeland War are considered in the Theoretical Part, also defining the terms of flag and vexillology.
The historical and social development of flag as identity symbol of military unit is presented. Their history on the Croatian land was specially considered as well as their modern development in the Homeland War and afterwards. The thesis presents results of research of more then 350 flags of the CAF units, expressing a whole spectrum of identity layers. Two kind of symbols may be noted in them: the main, with totemistic character and the auxiliary, with ornamental function. As the national symbol, beside the chequy coat of arms and the tricolour, a wattle ornament appears considerably. The tendency of use of darker dimmer colours during the War, and brighter colours afterwards. Also, a clear tendency of systematization of the flag design with time is remarkable.
The scientific contribution of the thesis is the introduction of vexillological methodology and linking it with sociology, as the base for an interdisciplinary appruach to the flag research. It presented and on the researched corps of flags applied elements of vexillological analysis.