Purpose: Loyalty is an ambiguous and complex phenomenon that may set the individual in dilemmatic situations. One assumption is that the individual’s level of fusion with his or her social identities also indicates where the individual’s strongest loyalty lies. Another assumption is that social identity fusion and hence the object of prioritized loyalty is influenced by the present context.

Design/Methodology: The study is based on longitudinal questionnaire data collected among staff of a Swedish military unit, two months prior to an international deployment in Mali (May 2018) and during the mission (September 2018), while the follow-up wave will be collected two months after the end of the mission (December 2018).

Results: The analysis and data collection is ongoing. Preliminary results from an initial pilot test with 160 military officers attending a course at the Swedish Defence University indicates satisfactory measurement properties and that social identity fusion is associated with loyalty towards certain ingroups.

Limitations: The study needs replication with larger samples from various settings before any conclusions regarding the generalizability of the association between identity fusion and loyalty can be drawn.

Implications: This study contributes to a better understanding of the loyalty concept within organizations that operate in extreme contexts.

Originality: This is one of the first studies to investigate how social identity relates to loyalty towards different groups, and whether these associations differ in extreme contexts such as an international military mission.