According to a BBC report the Belgian farmer moved the stone dating from 1819 that marked the France-Belgium border because it was in the path of his tractor. He relocated it 2.29 metres (7.5 feet) into French territory, thus making Belgium larger and France smaller.
Local authorities will request that the farmer replaces the stone to its original location to avoid the reconvening of a Franco-Belgian border commission that has been dormant since 1930.
The BBC report can be found here.