As the 10-man patrol picked its way down the lakeside track, the pine forest ahead suddenly erupted with gunfire.
The Ukrainian troops took cover and fired back at their unseen ambushers, throwing smoke grenades to cover their retreat, while bandaging up a wounded comrade writhing on the ground.
Moments later, as armoured personnel carriers sped to their rescue, the men clambered aboard and departed to be debriefed by British Army teachers watching the drill from a nearby rise.
In Western Ukraine, a small force of British trainers is trying to teach the beleaguered Ukrainian army battlefield skills that will keep them alive against more heavily-armed Russian-backed separatists.