Blueberries for the Queen — Katherine Paterson

It's summertime in New England during World War II, and a boy named William likes to imagine at bedtime that he is a brave knight fighting great battles to end the war. But in the morning he is always just William again, not big enough to contribute to the war effort like the rest of his family. Then a real queen moves in just down the road: Queen Wilhelmina of the Netherlands. Now William has his chance to do something. It may not be "war work"--it's more like peace work--but that makes all the difference.