In June of 1777, the “marine committee” in Congress passed a flag resolution authorizing the creation of an American flag. They even specified that it contain thirteen stripes, red and white and thirteen stars on a blue field. They did not specify how those stars and stripes ought to be arranged, or how many points the stars should have, etc. Francis Hopkinson, Congressman from New Jersey and a signer of the Declaration of Independence, was also a flag designer. He claimed to have produced the first flag in compliance with Congressional order, although his original drawings have been lost. He designed a stars and stripes to be used as a naval banner, since he was on the committee that oversaw naval affairs. He billed Congress for the design. Vexilology experts (those who study the science of flags) claim that the idea of a national flag was relatively new, although a number of banners had already been sported on battlefields and camps.
Whatever banner George Washington accepted prior to the Battle of Brandywine, it did not prove to be standard issue yet, since he complained to Congress in 1779 that no standard flag had yet been adopted for the armies to use in battle. Nonetheless, it seems that individual state units carried Stars and Stripes by the time of the battle. A Captain of the British 33rd Foot captured the home of a militia colonel a few days before the Battle of Brandywine and seized a stand of colors, one of which was “of dark blue fringed silk with a canton of thirteen red and white stripes.”