While Washington's heroic crossing of the Delaware may be firmly implanted into the American psyche, the truth is actually a whole lot stupider than what we were taught in history class. It turns out a loyalist spy named Moses Doan observed Washington along the Delaware on Christmas Eve, along with what he described as "a boatload of soldiers." He immediately notified Col. Johann Rall of the Hessians about the impending attack but was turned away because the colonel was engaged in a heated game of chess -- or, depending on who you ask, a poker game.
Since the colonel had no wish to be disturbed, Doan left him with a note that read: "Washington is coming on you down the river, he will be here afore long." Rall, still deeply engrossed in his game, stuffed the note into his pocket without giving it a thought.
Sure enough, Johann Rall was found dead the next morning, his little "Washington is coming on you down the river" note still unopened in his pocket.
... And that's why America exists.
The source is Clayton P. Yoder's book "Delaware Canal journal: a definitive history of the canal and the river valley through which it flows".
The crossing of the Delaware River by General Washington was on December 25, 1776. If the Doan in the note is indeed Moses Doan, he was shot and killed on September 1, 1783, during some confusion moments after he submitted to the authorities over a robbery years earlier of the Bucks County Treasury.