'Golden day' is a myth: rethinking medical timelines and risk in large scale combat operations.

The evolving landscape of battlefield medicine forces medical planners to prepare for large-scale combat operations (LSCO) against peer adversaries, requiring reassessment of recent medical strategies. Despite lacking medical backing, the term 'golden day' has been used by senior military leaders to link the resuscitative benefits of the 'golden hour' to prolonged medical care through similar nomenclature. Pseudomedical terminology can easily enter the lexicon of commanders as attractive soundbites. However, articulating the evidence-based factors influencing mortality on the battlefield is critical to effectively articulate risk to commanders. The challenges of LSCO will be significant with increased casualty numbers and treatment constraints. Realistic medical and operational planning is critical to maximising survival, with a clear understanding of what can and cannot be achieved. Recent improvements in trauma care, such as early haemorrhage control, advanced prehospital care and rapid evacuation to surgical care, have significantly reduced mortality rates. Given the predictability of when casualties die from significant injuries, the absence of timely clinical interventions will increase avoidable battlefield deaths. If evacuation to surgical care is extended to 24 hours, many more casualties will die from potentially survivable injuries. Medical planners must recognise the potential challenges associated with LSCO including contested, delayed evacuation which predicts a tripling of mortality rates from 10% to 30%. Leaders must appreciate the unchanging human physiologic response to injury and historical combat casualty statistics when preparing commanders and politicians for the excess in mortality during LSCO. Without candour, plans will be unrealistic, causing non-medical leaders and the public to be unprepared.