This paper discusses threshold concepts in Military Officers Education (MOE) at military institutions that also provide tertiary level education. In this study, threshold concept theory provides a helpful analytical tool to examine the process deemed necessary for transformation from civilian status to thinking and practising as a soldier and consequently a military officer. Combined with phenomenography as the research methodology, the research involved seven higher ranking officers, 24 military trainers, and 29 officer cadets from two reputable military education institutions in Europe. The findings show that there are two ontological shifts that transform a civilian to become an officer. During Phase I, the first ontological shift in becoming a soldier involves the acceptance of discipline and obedience, recognition of a framework of related ethics and values, loyalty to the unit (collective above individual needs) and a sense of obligation. Meanwhile, Phase II will require a soldier to understand the concept of personal responsibility for the execution of mission, putting others before self, and the 'power to command' to complete the transformation in becoming a military officer.