The 78-year-old is backing a drive to erect a statue in Walton-on-the-Naze in Essex, England in memory of Private Herbert Columbine, who died in the trenches in France just months before the war ended in 1918.
He was awarded a posthumous Victoria Cross, Britain's highest military decoration for valour, for his efforts in a battle with German troops, reported Daily Star.
Officials at the Royal British Legion have been raising money to fund the statue project, and Dench helped out by donating a signed photograph to bring in bids at auction.
The statue is due to be unveiled in 2014.
