Archaeologists have uncovered a piece of WWI history some 80 miles south of London, all thanks to a 1951 photograph. A British conservation officer poring over an aerial photo spotted something suspicious near the edge of one: crenellated lines (picture the notched top of a castle). Rob Harper's investigation of the site in Gosport, Hampshire—which had long been cloaked in "bracken and gorse"—turned up what the Guardian describes as a "lost first world war landscape," a practice battlefield where soldiers would have logged time in the trenches before being shipped to the mainland. Over many acres, Harper found "trenches everywhere": an overgrown but "perfectly preserved" training ground outfitted with frontlines (both the Brits' and the enemy's), a "no man's land" in between, and communication and supply trenches, reports the BBC.
"It's quite jaw-dropping really," Harper says of the find, which conservation body English Heritage announced yesterday. A wartime archaeology expert says the roughly 20 other mock battlefields that have been uncovered across England pale in comparison to the size and state of this one—of which no written record has yet been found, though historians are now on the hunt for such documentation. A historian explains the site's significance: "This is where you can see on the ground that it wasn't just about rounding up young men and hurling them at the machine guns: They were being incredibly well trained." One archaeologist adds that small slit trenches that appear throughout the complex may have been new soldiers' first attempts at trench digging. (Click to read about another war-related discovery: WWI mummies.)