Armed conflicts around the world expose members of defence forces to ever more traumatic events. However, figures for suicide after leaving the UK Armed Forces from 1996 - 2018 indicate that deployment was associated with a reduced risk of suicide, which was greatest in veterans aged under 25 years, including those who left the Armed Forces without completing their training. Similarly, in the United States, there are more attempted suicides during training than at war. Studies of military personnel have shown that dissociation is a frequent accompaniment to military training, especially of the more extreme kinds, and that dissociation is associated with an increased risk of suicide, especially amongst those who have experienced childhood trauma.

To examine and review the nature and extent of dissociation as a possible complication of military training and a risk factor for suicide.

A brief overview is given of the figures from the UK suicide study and continues with an explanation of dissociation and its appearance during military training. Next, the connection of dissociation to self-harm and suicide is explored, as well as the influence of previous childhood adversity.

The incidence of dissociation amongst military personnel is high at all levels of training, and even if considered as an adaptive response under stress, it does not improve military performance. It is associated with increased risk of self-harm and suicide, notably in younger age groups, and is heightened by previous trauma exposure, especially in childhood, as well as bullying and assault by training staff and peers.

The relative contributions of training and previous childhood trauma are discussed, and directions for future research and policy are suggested.

It is vital that all trainees are monitored for this overlooked phenomenon. Screening for previous childhood trauma is also recommended. However, a person's background must not be used as an excuse to evade the issue of inhumane treatment during military training.