Flag of the Thirteen Colonies (Grand Union Flag) - Historical American Symbol #1485474 (License: Personal Use)

This historical flag, also known as the Continental Colors or Cambridge Flag, was first flown on January 1, 1776, at Prospect Hill during the Siege of Boston. It combined the British Union Jack in the upper-left corner with thirteen alternating red and white stripes, symbolizing unity among the colonies while still acknowledging ties to Britain. Its use was short-lived, replaced by the Stars and Stripes after the Declaration of Independence in 1777.

Used on history, education, and museum websites to illustrate early American revolutionary symbolism; matches user intent for learning about U.S. flag evolution, colonial history, or military heritage.