The hogs rooted through almost the entire Ostfriedhof cemetery in the cathedral city's Dellbrück district in a bid to unearth delicious worms.
"They've been plaguing us for weeks. They haven't spared a single plot," one cemetery worker told Cologne's Express newspaper.
"The animals can't find good sources of protein in the woods at the moment," Manfred Kaune, head of the city's parks department, told the Kölner Wochenspiegel.
Although the workers have tried everything from burning incense to reinforcing fences to keep the wild swine away, nothing has so far proven effective at holding back their hunt for grubs.
The last resort was to form a human chain through the cemetery, using loud noises including gunshots, banging pots and pans and shouting through a megaphone to scare the hogs back into the forest.
Even that didn't work, leaving the puzzled humans to regroup and reflect on new tactics.
Cologne's town hall website offers advice on dealing with wild boar, which "have multiplied strongly and spread into outlying areas of the city" in recent years thanks to "favourable living conditions."
"Keep calm. Boars usually run away. Stand still, make yourself visible, don't run away but walk slowly backwards," the advice reads. "Leave the animals an avenue of escape."
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Citizens are encouraged to call the police if a boar presents an immediate danger to the public.
Meanwhile, for securing outdoor areas against their intrusions, the city recommends an electric fence – perhaps the next upgrade for the cemetery.