Union Jack , also called the Union Flag, is the national flag of the United Kingdom of Great Britain and Northern Ireland. The flag contains the three national crosses of England (St. George’s cross), Scotland (St. Andrew’s cross), and Ireland (St. Patrick’s cross). The crosses overlap on a blue field. The Union Jack’s present form has been in use since the union between Ireland and Britain in 1801. A jack is a national flag generally flown by warships.
