Union Jack Union Jack The Union Jack, or Union Flag, is the national flag of the United Kingdom. The flag also has an official or semi-official status in some other Commonwealth realms: for example, it is a ceremonial flag in Canada by parliamentary resolution, and known there as the Royal Union Flag. Further, it is used as an official flag in some of the smaller British overseas territories. The Union Flag also appears in the canton (upper left-hand quarter) of the flags of several nations and territories that are former British possessions or dominions, as well as the state flag of Hawaii.
Union Jack and submarines of the Royal Navy, and by commissioned army and Royal Air Force vessels. When at anchor or alongside, it is flown from the jackstaff at the bow of the ship. When a ship is underway, the Union Jack is only flown from the jackstaff when the ship is dressed for a special occasion, such as the Queen's official birthday. The Union Jack is worn at the masthead of a ship to indicate the presence of the Sovereign or an Admiral of the Fleet. The Union Flag may also be flown from the yardarm to indicate that a court-martial