Now widely known as the mental disorder PTSD, the condition often afflicts military personnel.

University of Newcastle Professor Philip Dwyer is researching the effects of war trauma on civilians and combatants.

The project, titled Aftermaths of War: Violence, Trauma, Displacement 1815-1950, will investigate the cultural, social and psychological consequences of wars.

"We now know quite a bit about the trauma associated with warfare, or the aftermaths of war, but generally only in relation to veterans," Professor Dwyer said.

"This is not so much the case for civilians who have lived through war."

In the modern era, civilians were increasingly caught up in conflict and "often deliberately targeted".

The study will look at civilian displacement [refugees] and how countries and the international community have responded to them.

It will also examine how civilians themselves "live and remember the trauma they have experienced".

"We're not entirely sure what the long-term legacies of warfare for civilians are yet," he said.

"But there are two sides of that coin that we want to explore: those civilian refugees fleeing violence and who may have experienced it; and those civilians on the homefront who have to deal with traumatised and possibly even brutalised veterans when they return."

When these veterans return, their traumatic experiences can have immense and extended effects.

"That trauma is often passed down from one generation to the next, possibly even epigenetically according to some scholars."

While trauma existed in the early 19th century, "people didn't understand it in the same way that we do today".

Professor Dwyer, director of the Centre for the History of Violence, said PTSD was invented "post-Vietnam".

"During the war itself, psychiatrists diagnosed what they called Post-Vietnam Syndrome," he said.

For generations, there was a refusal to acknowledge the condition, which has also been called shell shock and battle fatigue.

"The French called it an 'alienation of the mind' in the early 19th century - but didn't know how to recognise it or treat it."

The research is a collaborative project that involves a number of historians from around the world.

"We are attempting to write a comparative history from 1815 to 1950, touching on Europe, Australia, the US, Japan and China and the Middle East," Professor Dwyer said.

They're looking at 19th century European wars like the Crimean War [1853-56], Franco-German War [1870-71], the American Civil War [1861-65], the first and second world wars and their aftermaths.

"We're just at the beginning of a long process. Funding started in March and then COVID began," he said, adding that the pandemic had "put things on hold".

Professor Dwyer highlights the need for "moral courage" during war.

Without moral values instilled in the military and "knowing where to draw the line between right and wrong", atrocities would be committed.

He said there were "all sorts of reasons why a soldier might cross that moral line".

Peer group pressure is one example.

"But once it's crossed there is no turning back," he said.

A commander in the field may "allow something to happen - may even approve of it".

"Then his men have been given the latitude to commit crimes and to think about killing in ways that they wouldn't normally," he said.

The commander, who represents a form of middle management, must "set an example".

"But that example and that moral compass has to come from the top," he said.

When an atrocity is committed during a war and the army fails to respond adequately, it is "due to a moral failure of command".

Moral failure is a concern that has been raised amid allegations against Australian special forces in Afghanistan.

The Inspector-General of the Australian Defence Force is investigating 55 allegations of special forces soldiers unlawfully executing and abusing civilians and prisoners in Afghanistan from 2005 to 2016.

Secret defence force documents leaked to the ABC allegedly revealed cases of Australian troops killing "unarmed men and children".

The special forces have been accused of a culture of covering up alleged abuses, Professor Dwyer said, citing an ABC Four Corners investigation broadcast in March.

"If previous wars and crimes are anything to go by, then I can't see any individuals, and certainly not officers, being held to account. I hope I'm wrong," he said.

US and British special forces have also been accused of war crimes in Afghanistan.

"Wherever the military interacts with civilians in number and over a period of time, atrocities, rapes and massacres are bound to happen," Professor Dwyer said.

"They happen for all sorts of different reasons - each atrocity and massacre has its own history - but it appears to be an inevitable part of warfare.

"Those who witness it and those who commit the atrocities will, no doubt, be plagued with their memories for the rest of their lives. Very few people, maybe sociopaths, will come out of it unscathed."

The Vietnam War was a prime example of moral boundaries becoming blurred. It came to a point where every Vietnamese person was regarded as a potential enemy.

"I suspect the same sentiment might prevail among the military in Iraq and Afghanistan," Professor Dwyer said.

The Vietnam War was "televised into our living rooms". Now we only see "what the army wants us to see".

"We now rarely see the ugly face of war - except when journalists uncover something - and certainly not to the extent that civilians were exposed to it during the Vietnam War."

He wonders whether this is why the Afghanistan War - which began in 2001 - has "dragged on for so long".

News of the Afghanistan War, he said, was "sanitised" and seen only "at a distance".

"A drone strike, a bomb exploding on a target. We rarely see the aftermaths, the human debris, the burned and dismembered bodies."

As a boy of 10 or 11, Professor Dwyer distinctly recalls seeing the execution of Viet Cong prisoner Nguyen Van Lem by the Vietnam general Nguyen Ngoc Loan.

"I was confused. Wasn't he [the general] supposed to be on our side? We were the good guys. How could he have done that?"

The image was shown on TV during the Tet Offensive in 1968. The photo - dubbed Saigon Execution - showed the microsecond the bullet entered the head of the prisoner. It changed the course of the war and strengthened opinions in the US that the war could not be won.

As for war generally, Professor Dwyer said humanity "seems to have a short memory".

"The generation that has experienced war is most likely to be against it," he said.

"Those who have never encountered it face-to-face are more likely to have romantic notions of what it is about."

He said the media - including films - often portray war as an adventure and a challenge.

In this sense, war was depicted as "a kind of initiation into manhood, that makes many young men only too willing to sign up for service".

"Think of all those who joined the US military after 9/11. It's the kind of sentiment that can be found across time and cultures."

Professor Dwyer said his grandfather - at age 16 - joined the Australian Imperial Force of the Australian Army during World War I.

"I think he saw it as an adventure, maybe as a duty."

He joined when WWI had been going on for a few years.

"He would have known about the casualty rates, but still signed up," he said.

"The ways in which we commemorate wars and glorify veterans - who are all transformed into 'heroes', regardless of their own personal histories or moral character - doesn't help."