Even 400 years ago, William Shakespeare understood the bonds forged by war. His words, spoken by Henry V as his 15th-century English army prepared to face the French at Agincourt, remain a useful reminder:

We few, we happy few, we band of brothers;

For he who sheds his blood with me this day shall be my brother.

But another outcome of war was often unspoken, if not taboo: the mental toll faced by veterans of combat.

Besides physical injuries, the Canadian military must also deal with wounds to the mind for soldiers returning from Afghanistan and other missions.

Post-traumatic stress disorder (PTSD), also known as operational stress syndrome, tends to afflict military personnel, emergency services workers, and journalists who witness tragedy or trauma. Symptoms range from poor concentration and insomnia to depression and emotional numbing.

Previous generations used the terms "shell shock" or "battle fatigue" to describe the horrors of World War. But the words describe the same problem: a world made dark by terrible flashes of memory.

Arthur Smyth still struggles to cope with his time at a Canadian base in the Persian Gulf.

"The threat's always there. Tension is always there," he told CTV Ottawa.

"It's something new to the military. Our role has always been peacekeeping and all of a sudden we're in war zones where people are actually getting killed."

A military culture infused with machismo and a stiff upper lip had problems dealing with mental health as recently as the mid-1990s. The stigma remained strong, and soldiers faced being singled out, said Scott Taylor, publisher of Esprit de Corps magazine.

Gen. Romeo Dallaire's highly public battle to make peace with the anguish of Rwanda's 1994 genocide helped break the barrier. He was candid about the aftermath of forcing to stand aside as commander of a United Nations mission while hundreds of thousands were massacred.

"If you've got somebody who's hurting and goes back to another mission, you've just got a catastrophe waiting to happen," said Dallaire, now a senator after a high-profile exit from the Canadian Forces.

It's a different world now from when an old soldier said: "if the military wanted you to have feelings, they'd have issued them."

Some soldiers can't perform their job afterwards because of intrusive thoughts, nightmares, and flashbacks, said Dr. Marvin Westwood, a psychology professor at the University of British Columbia.

Butt he very fact that soldiers are willing to discuss their problems is an improvement, according to Dr. Rakesh Jetly, a military psychiatrist.

"The idea that very senior, hard-as-nails infantry type people come in and say 'hey, Doc, would you mind if we talked to you, would you mind seeing my guys over a cup of coffee,' I think we've come a long way there," Jetly said.

With a report from CTV Ottawa's Norman Fetterley