Peace protesters inscribed a message on a hillside to look like a giant historic etching against war.
The prominent graffiti could be seen by hundreds of motorists on one of the busiest routes in Sussex, about a mile from the authentic chalk cutting, the Long Man of Wilmington.
The word Peace appeared overnight on the side of Mount Caburn near Lewes, one of the county's best-known peaks, in giant letters spelled out in white emulsion paint.
The protest could hardly be missed by drivers on the A27 and A26 near the Beddingham roundabout.
Officials at English Nature, which manages the site, were preparing to remove the message this morning. They are not confident of catching the culprit.
However, some residents applauded the mystery painter's initiative. Sarah Mayer, from nearby Rodmell, thought the sign sent out an important message.
She said: "It's great. I really like the idea. I hope it will make people think.
"We are only a small village but 19 of us went up to the London march on February 15.
"We may be in the countryside but there are strong opinions here."
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