Flags flown from a warship include the national ensign and the jack. The jack and Navy jack are different flags. But first let us find out why they are called jacks.

The jack simply got its name from where it is flown while in port, the jack staff. The jack staff is the pole at the front of the ship where a flag is flown while in port. Ships fly flags from the bow and stern while in port, but amidships while underway. So the flag on the jack staff is called a jack.

There are two different jacks flown in the Navy. The first one every ship flies, except one. This one is the standard jack, a blue flag with 50 stars. This flag has been used since July 4, 1960. Prior to this, just as the national flag, the number of states dictated the number of stars. Once again this flag is only flown while in port.

The other jack used is the First Navy Jack. It is a flag with thirteen red and white stripes, similar to the national flag, with a snake and the phrase, “Don’t Tread on Me”. This flag is flow by the oldest US warship, currently the USS Kitty Hawk. It is also flow Navy wide on special occasions. Most recently it has been associated with the War on Terror. Instruction 10520.6 issued by SECNAV allowed all ships to use the flag on a temporary basis.

A unique side bar on the First Navy Jack is there is no historical evidence that it was ever flow on any Navy ship when the Navy was founded. It is suspected that the flag status of the flag came from the 1880 book by Admiral George Henry Preble's influential “History of the Flag of the United States”.