"The Second Day of July 1776," John Adams wrote to his wife Abigail, "will be the most memorable Epocha [fixed moment] in the History of America… it will be celebrated… as the great anniversary Festival." Perhaps only John Adams realized that delegates to the Continental Congress had given birth to the modern national holiday, which came to be celebrated on the fourth, when the Declaration of Independence was approved. The day, he told Abigail, "ought to be commemorated, as the Day of Deliverance… It ought to be solemnized with Pomp and Parade."

The Fourth of July provided a rallying point for revolutionary fervor throughout the war. The Continental Army celebrated by firing salutes, distributing extra rum, and pardoning prisoners. Holiday rituals included bell ringing, thirteen-gun salutes, fireworks, military parades, oratory, sermons, dinners, and toasting. A consensus emerged on these rituals and the national symbols of...