Night of Soldiers and Spies (Ranger in Time #10) : Volume 10 (Ranger in Time)

Ranger the time-travelling Golden retriever and young Isaac Pope come together in 1776 during Washington's retreat after the Battle of Long Island, and Ranger stays with Isaac while he slowly recovers from Smallpox--but Ranger's real mission comes later when Isaac is sent to spy out the Hessian troops' intentions before the Battle of Trenton.