The UNION JACK — the national flag of the United Kingdom — combines blue, red, and white, each with deep historical and symbolic meaning.

The Union Jack unites the crosses of three patron saints:

St. George (England) – Red cross on a white field

St. Andrew (Scotland) – White diagonal cross (saltire) on a blue field

St. Patrick (Ireland) – Red diagonal cross on a white field

These were merged over time to form the modern Union Flag (commonly called the Union Jack).