On this day in 1860, Boston newspapers carried an advertisement for an extraordinary event: photographer James Wallace Black would photograph Boston from a hot-air balloon hovering over the city. Black accomplished this well-publicized feat five days later, and the Boston Herald soon printed the nation's first-ever birds' eye view of the earth below. It was the first aerial image taken in the United States, the first aerial image of a city anywhere, and is the oldest aerial image known to survive. While the public marveled, the United States Army was quick to see the military value of Black's stunt. Union photographers in hot air balloons were soon tracking Confederate troop movements, providing the world's first aerial reconnaissance.