Anyone who decides to tour the battlefields of Trenton and Princeton should first read Richard M. Ketchum’s marvelous book The Winter Soldiers , which tells of those trying months with verve and intimacy. Unfortunately Sol Stember’s 1974 Bicentennial Guide to the American Revolution is out of print, but try to get a copy at the library; it is endlessly useful and exhaustive in its detail. When you’re in Trenton, find time to have a drink or a meal at the Eagle Tavern on South Broad Street; it stood as a private home in Washington’s day and soon after became a tavern; there are places that have been more finickingly restored, but somehow the Eagle’s interconnecting dining rooms radiate easy authenticity. Finally, after seeing Princeton, you won’t be sorry if you drive back to the Delaware and up Route 29 to Stockton, where Colligan’s delightful inn, built as a house a quarter-century before Washington was born, has been serving food and drink to travelers since 1832. And if you want to pull out all the stops, come to Trenton on Christmas Day itself, and you can be part of the crowd that annually gathers on the cold riverbank to watch a reenactment of the Delaware crossing. Both the Pennsylvania and New Jersey departments of tourism can help you plan your trip; for Pennsylvania, call: 717-787-5453; for New Jersey, 609-292-2470.