It soon becomes clear no live rounds will be fired today. This is an exercise. But the shooting may soon be for real, if or when the Croats try to recapture the territory the Serbs took four years ago in autumn 1991.
Milena, a former bookkeeper, said: "We are obsessed with the danger of war. We talk about it all the time." A farmer said: "People don't have the will to work or do anything. We see what they say on Croatian TV and we are just waiting. Waiting for the attack to come."
Visiting this area now, while politicians acclaim this week's deal in New York, gives a sense of deja vu. When I was here in July 1991, there was no mistaking the war that was about to explode. I huddled behind a wall as the next house was destroyed in a battle in which only one Serb and one Croat died. The neighbours were terrified of what would soon engulf them.
Back in my hotel room I listened to the news headlines: triumphant statements by European leaders following the deal to end Belgrade's little war against the breakaway republic of Slovenia. It was a surreal moment: Belgrade's military amuse-gueule, in which a few dozen people died, seemed to the statesmen to be the Main Event while the looming catastrophe here was a sideshow.
The contrasts today are equally striking. In New York they talk of a turning point. In eastern Slavonia the fear of a renewed Serb-Croat war is everywhere. Freshly-painted signs point every few hundred yards to SKLONISTE. Skloniste means "shelter" - bombed-out houses (destroyed by the Serbs in 1991) where Serb villagers can hide in cellars when the Croat shells start to fall.
Milka and Vlasta, two nurses from nearby Borovo, sit waiting by the side of the road on duty for what they regard as the inevitable. Vlasta, six months pregnant, says: "You have an awful feeling when you see what's happening. We're expecting the attack. But God save us when it comes." A Red Cross flag marks the field hospital she and her colleagues have built in a cellar. Throughout the region posters proclaim it is every Serb's duty to fight. "Daddy", says one poster, showing a soldier's big bootprints above a pair of tiny handprints, "whether or not we grow up depends on your decisive steps".
The Serbs seized this territory in autumn 1991 and laid it waste. The Croats were then in the majority. Now there are almost no Croats left. Vukovar was famously destroyed in a brutal siege. But it was not just Vukovar: the entire landscape is still haunted by death. Mortar shells lie embedded in the road; weeds grow in the gaping ruins; smashed traffic lights stand twisted and useless; children build military shelters, and play at Serb-Croat war.
Franjo Tudjman, the Croatian President, appears punch-drunk with his successes in southern and western Croatia, where the Croatian army seized the entire region. About 200,000 Serbs were driven out. Eastern Slavonia is next on his list.
Slobodan Milosevic, the President of Serbia, allowed the Serb-majority areas of Croatia to be overrun with scarcely a murmur. But it is unclear whether he could afford the extra humiliation of losing eastern Slavonia without suffering a serious political defeat at home. For Mr Milosevic, this is the only consideration.
Already thousands of Serbian refugees have flooded into this area in recent weeks, driven from their homes by the Croat offensive. In Erdut alone, 150 people queue up every lunchtime for a Red Cross bowl of soup. Many break down in tears when contemplating the possibility that they might be overtaken by war again. Dara Krtinic travelled for 27 days with her husband by horse and cart before reaching Erdut. "The Croats threw us out. We had two houses, pigs, everything. How can we now go back? But how can we stay if they come? And where else can we go to?"
War in eastern Slavonia is not inevitable. But if the West fails to put pressure on Zagreb (as it failed to do over the recent expulsions of Serbs from their homes in Bosnia), a new war will be a fait accompli. It will seem as certain as the war of 1991 seemed more than four years ago, when politicians crowed about peace and distraught villagers waited for war.