Boys Start the War — Phyllis Reynolds Naylor

Just when the Hatford brothers were expecting three boys to move into the house across the river where their best friends, the Bensons, used to live, the Malloy girls arrive instead. Wally and his brothers decide to make Caroline and her sisters so miserable that they'll want to go back to Ohio, but they haven't counted on the ingenuity of the girls.

From dead fish to dead bodies, floating cakes to floating heads, the pranks and tricks continue -- first by the boys, then by the girls -- until someone is taken prisoner! Will the Malloys leave West Virginia? Will the Bensons come back? Trust the four Hatford boys and the three Malloy girls to do anything to win this fun-filled war of wits.