Singer Chris de Burgh has paid £14,400 for a letter written by an unknown soldier describing the Christmas Day truce in 1914.
The letter describes how soldiers exchanged cigarettes and clothes
The document is one of the few first accounts of the famous event when German and British troops briefly halted hostilities at Ypres, Belgium.
Signed simply 'Boy' the hand-written 10 page letter was penned by a young soldier whose fate remains unknown.
De Burgh made a telephone bid for the object when it came up for sale.
London auction house Bonhams had expected the item to fetch around £400.
Lady in Red singer De Burgh, 58, said he was fascinated by the truce.
"I am totally passionate about the subject. I read every line of the letter and found it an extremely moving and personal account of World War One," he said.
"The letter is a great historical document charting the surreal events of the 25 December 1914."
De Burgh added that his great uncle, Thomas de Burgh, was thought to be the first officer killed in the war, and his body was never found.
His grandfather also served in the trenches.
In the letter, dated 25 December, 1914 and addressed to "My dear Mater", the soldier wrote: "The Germans commenced by placing lights all along the edge of their trenches and coming over to us - wishing us a Happy Christmas etc.
"They also gave us a few songs etc. so we had quite a social party."
He went on: "They say they won't fire tomorrow if we don't so I suppose we shall get a bit of a holiday - perhaps.
"After exchanging autographs and them wishing us a Happy New Year we departed and came back and had our dinner.
"We can hardly believe that we've been firing at them for the last week or two - it all seems so strange."