War and disaster are forcing a major rethink around mass casualty management.

Mass casualty events (MASCAL) do not follow the same rules as typical major incidents. In the West at least, the latter often occur in stable, networked trauma systems, whereas MASCAL are characterised by overwhelming numbers of patients, compounded by protracted scene and transport times, decompensated response systems and significant disruption to infrastructure, command and control.This paper describes the 8Ds approach being taken by the UK Defence Medical Services and the North Atlantic Treaty Organization Emergency Medicine Panel framework to approach MASCAL. The eight domains were derived from literature about management of casualties in the World Wars, and also from approaches taken by civilian health systems as they struggle to manage increasing demand. They are: distribute; decompress; delay; delegate; deliver faster and deliver better; dynamic levels of care; and de-escalate These domains will allow a structured approach to research and innovate around MASCAL, informing better guidelines for their management.