The trouble began with words, not weapons. An 1881 treaty meant to fix the border between the two republics, and an 1893 protocol that followed, used language that could be read two ways. Argentina insisted the boundary should follow the highest peaks of the Andes; Chile argued for the continental watershed, the line dividing rivers that flow to the Atlantic from those bound for the Pacific. In the Patagonian ice, where high peaks and watershed do not neatly coincide, those two principles tore apart. In 1902 the British crown was called in to arbitrate, and King Edward VII issued an award — but it deliberately said nothing about the ice field itself, judging that there the high peaks divided the waters and so no real dispute existed. That silence would echo for a hundred years.

By the late twentieth century the old ambiguity had hardened into open friction. In 1994 an international tribunal ruled on the Laguna del Desierto dispute, a contested patch involving the ice field's eastern flank, and awarded almost the entire zone to Argentina. Chile appealed, lost, and in 1995 accepted the verdict — a loss still remembered south of the Andes as a national wound. The decision left Chile with only a narrow corridor to reach Mount Fitz Roy, and the Marconi Pass was designated as the official border crossing into that sliver of ground. For Argentina it was vindication of the high-peaks principle; for many Chileans it was a defeat that made the remaining ice-field boundary feel less like a technical loose end and more like unfinished business worth guarding.

In 1998 the two governments tried again, signing an agreement to trace the border from Fitz Roy south to Mount Daudet and to replace an earlier zigzag proposal. They divided the work into two stretches. Section A, running from Cerro Murallón down to Daudet, was drawn and settled, following watershed and a chain of named peaks — East Torino, Agassiz, Spegazzini, Stokes. But Section B, the leg from Fitz Roy north to Murallón, was left deliberately open. The two sides agreed it would wait until a detailed map at 1:50,000 scale could be surveyed and negotiated. That survey was meant to close the file. Instead, the rectangle between those parallels became a permanent blank — a stretch of border both nations had agreed, in writing, to leave undefined for now.

With no soldiers contesting the ice, the dispute migrated onto paper. The fight is now fought in cartography. Argentine maps tend to omit the white rectangle marking the undefined zone, drawing the boundary as settled; Chilean maps insist on showing the gap and noting that the line is not defined. Each accuses the other of claiming roughly a thousand kilometers more ice than it should. The clashes have been almost comic in their politeness and almost serious in their stakes — a 2006 summit between presidents Michelle Bachelet and Néstor Kirchner over a tourism map; an Argentine glacier inventory in 2018 that Chile formally protested; a research dome erected by Chile's forestry corporation at the Circo de los Altares, whose southern half both countries claim. No one has fired a shot. Both simply keep redrawing the same emptiness, each certain the ice is theirs.