A Belgian farmer accidentally annexed France by moving a rock. What does it say about borders?

This week, a farmer in the Belgian town of Erquelinnes caused an international ruckus when he moved a stone standing in his tractor’s path.

This stone marked the boundary between Belgium and France. By moving it 2.29 metres, he expanded Belgium’s territory.

We must assume he had driven around it before – the stone was placed on this site in 1819, as part of the proceedings that established the Franco-Belgian border in 1820 after Napoleon’s defeat.

For the farmer, it stood in the way of his tractor. For the governments of France and Belgium, it was an active international border.

This story suggests a fragility to borders that contradicts their apparent solidity in an atlas or on Google Maps. Human history is, however, full of arguments about where the edges of property lie.

‘Beating the bounds’

Nations establish their borders through treaties. Rivers are sometimes relied on to set boundaries, but even here tensions rise when there are disputes about interpretation. Is the boundary on the river banks, the deepest part of the river, or the very centre of the flow?

The fact these measurements can even be calculated is remarkable. Expecting high levels of accuracy in a map is a recent development.

The first attempts at consistent accuracy were in 19th century military maps, such as Britain’s Ordnance…

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