The Canadian forces, digging to extend the five-foot trench they stood in, didn't hear the crunching of dry leaves as German soldiers sneaked up to attack them.
Dozens of high school students posing as Germans bombarded 30 neck-deep teachers with makeshift stick grenades during last week's reenactment of a trench raid.
These reenactments take place annually on history teacher Robin Barker-James's 50-acre farm in Tillsonburg, Canada, about two hours southeast of Toronto. Each year the two-day event grows, as does the maze of student-dug trenches. More than 2,000 15- to 19-year-old students have now participated in the depictions of World War I and II battles.
The exercise has had particular resonance this year, coming just a few weeks after Canadian forces left to take part in the US-led campaign against Afghanistan's Taliban regime.
Barker-James created the trench system four years ago, with the blessing of his wife, also a teacher, and his school principal. But, he notes, some local school boards objected to the idea, saying it was too militarist.
And indeed, he admits, some students do get a "glint of devil in their eyes" during the reenactment, and needed to be reminded of its educational purpose. But many more student participants believe the exercise has helped them to better understand the harsh realities of war.
"This is more of a deterrent to it," says 11th-grader Jay Tisdale, who played the role of a German command officer in the surprise attack. He says the battles reenacted show the "grimmer side" of war, not the romanticized Hollywood version.
Brooke Vanderhoeven, who participated this year for the second time, agrees: "Last year, I was really upset, because afterwards I couldn't believe what they went through."
Barker-James says that's the goal of the simulation: to leave students "hesitant about blindly supporting war."