American flag flown in battle, Sept. 3, 1777

On September 3, 1777, the Flag of the United States was flown in battle for the 1st time at Cooch's Bridge, Delaware, a skirmish during American Revolutionary War. From the article:

"On this day in 1777, an American flag flew in battle for the first time.

This occurred during a Revolutionary War skirmish at Cooch’s Bridge, Delaware. Gen. William Maxwell, commanding a Patriot force of infantry and cavalry, ordered the newly designed flag raised in a clash with an advance guard of British and Hessian troops.

The rebels were defeated and forced to retreat to the encampment housing Gen. George Washington’s main force near Brandywine Creek in Pennsylvania.

Three months beforehand, on June 14, the Continental Congress resolved that “the flag of the United States be 13 alternate stripes red and white” and that “the Union be 13 stars, white in a blue field, representing a new constellation.”

The new national flag, which quickly became known as the “Stars and Stripes,” was based on the “Grand Union” flag — a banner carried by the Continental Army in 1776 that consisted of 13 red and white stripes.

In a report to the delegates, Charles Thompson, the secretary of the Continental Congress, stated that the white in the flag “signifies purity and innocence,” the red “hardiness and valor” and the blue “signifies vigilance, perseverance and justice."

As new states entered the Union, both new stripes and stars were added to represent them. During the War of 1812 with Great Britain, a 15-star, 15-stripe flag inspired Francis Scott Key to write what later became known as “The Star Spangled Banner.” The flag is currently on display in the Smithsonian Institution National Museum of American History in Washington, D.C.

In 1818, Congress restored the 13 original stripes and decided that stars should be added only to represent newly admitted states."