War Stories Hardcover by Gordon Korman

There are two things Trevor loves more than anything else: playing war-based video games and his great-grandfather Jacob, who is a true-blue, bona fide war hero. At the height of the war, Jacob helped liberate a small French village, and was given a hero's welcome upon his return to America. Now it's decades later, and Jacob wants to retrace the steps he took during the war; from training to invasion to the village he is said to have saved. Trevor thinks this is the coolest idea ever. ...