International Relations (IR) scholarship on ontological (in)security has explored how political agents seek to shape collective identity through the contestation and securitisation of memory narratives around controversial historical events. This article contributes a novel approach for understanding how actors promote emotional engagement with such narratives, synthesising nascent scholarship on vicarious identity and military subjectivity to develop the concept of ‘militarised vicarious identity promotion’. I use this framework to analyse how national custodian, the Royal British Legion, used the British 2014–18 First World War (WW1) centenary to promote affectively resonant revisionism around a war with difficult resonances in Britain by encouraging subjects to ‘live through’ others. Its ‘LIVE ON’ and ‘Every One Remembered’ initiatives first countered the centenary’s potential to destabilise homogenised militarist narratives underpinning national ontological security by rehabilitating WW1 through vicarious frames blurring different military subjectivities together in ways designed to reincorporate WW1 into homogenised remembrance discourses. Second, Britons were encouraged to integrate the nation’s military history into their personal biographies by vicariously identifying with ancestral and adoptive WW1 connections. Through enabling feelings of pride and status assuaging civilian anxiety, ‘vicarious military subjectivity’ based on family connections provided emotional reinforcement for identification with simplistic WW1 revisionism and homogenised British militarism more broadly.