Private Herbert Lelliot, from Ashurst, was in the infantry of the 8th battalion of the Royal Sussex Regiment.
He was hit by German fire on the opening day of the Somme campaign on July 1, 1916.
Private Lelliot’s name is on the Thiepval Memorial.
The three First World War medals that were awarded to Private Lelliot’s family are known as a ‘Star Trio.’
They are with Lockdales auctioneers, of Martlesham, near Ipswich, where they will be auctioned on Saturday (July 9) as one lot.
They are expected to be sold for between £240 - £260.