In Nagorno-Karabakh, an ancient rivalry is driving a modern war and the losses are mounting

After a long, cold night on the frontline Sos and David returned to the building where they grew up and dropped their gear and AK-47 assault rifles to the floor, exhausted.

“The main enemy is panic. We teach that to our children,” says Sos, 30, and the father of a four-year-old boy. “The most important thing is self-control.”

For several days the Azerbaijan army has been besieging Sos and David’s hometown of Shushi — as it is known in Armenian — or Shusha in Azeri.

In the background, mortars and cannons are rumbling and the war’s frontline line sits just a few hundred metres away from their…