“Don’t Tread on Me” This is a traditional flag flow by the US Navy’s oldest warship. This honor is currently held by the USS Kitty Hawk. This honor will pass to the USS Enterprise when the Kitty Hawk is decommissioned. Ships normally fly a blue jack with 50 stars. Twice in recent times every ship in the Navy was allowed to fly the first jack, during the bicentennial and after September 11, 2001.

There is actually no historical proof of the first Naval jack design. In the autumn of 1775, as the first ships of the Continental Navy readied in the Delaware River, Commodore Esek Hopkins issued, in a set of fleet signals, an instruction directing his vessels to fly a "striped" jack and ensign. The exact design of these flags is unknown. The ensign was likely to have been the Grand Union Flag, and the jack a simplified version of the ensign, a field of 13 horizontal red and white stripes.

However, the jack has traditionally been depicted as consisting of thirteen red and white stripes charged with an uncoiled rattlesnake and the motto "Dont Tread on Me". This tradition dates at least back to 1880, when this design appeared in a color plate in Admiral George Henry Preble's influential “History of the Flag of the United States.” Recent research, however, has demonstrated that this inferred design never actually existed. It is more likely a 19th-century mistake based on an erroneous 1776 engraving.

In 1778, John Adams and Benjamin Franklin wrote a letter to the Ambassador of Naples, thanking him for allowing entry of American ships into Sicilian ports. The letter describes the American flag according to the 1777 Flag Resolution, but also describes a flag of "South Carolina, a rattlesnake, in the middle of the thirteen stripes."

The rattlesnake had long been a symbol of resistance to the British in Colonial America. The phrase "Don't tread on me" was coined during the American Revolutionary War, a variant perhaps of the snake severed in segments labeled with the names of the colonies and the legend "Join, or Die" which had appeared first in Benjamin Franklin's “Pennsylvania Gazette” in 1754, as a political cartoon reflecting on the Albany Congress.