The Union Jack
The British Union Flag colloquially known as "The Union Jack" is probably the most famous flag in the world.
It is the Flag of the United Kingdom of Great Britain and Ireland* (*Northern Ireland after 1923) but what does it mean?
The Kingdom of Scotland
Map of Scotland.
St Andrew’s Cross is blue with a white background, it is believed to be the oldest flag in Europe and the Commonwealth. The blue represents the sky which is why it is sometimes seen in Scotland as sky blue opposed to Royal blue when incorporated into the Union Flag (in my opinion the Royal blue colour goes better). The cross itself was carved out by the white clouds. As a sentiment to Scotland’s bad weather the blue sky and white cross was seen as a sign by King Angus in 832 AD from St Andrew in response to his prayer of deliverance. After he won the battle St Andrew was made the Patron St of Scotland and his saltire adopted. More details here.
Image from wikipedia.
The Kingdom of England
Map of England.
St George’s Cross is Red on a White background. This is a Christian Crosses thus red likely resembles blood, the blood of the martyr being crucified and white likely resembles purity and hope. See here for more details:
Click to access christianity.pdf
The Principality of Wales
Map of Wales
Wales Becomes a Principality of the Kingdom of England
Wales becomes a Principality of the Kingdom of England. In the Union Flag St George's Cross thus represents The Kingdom of England and Principality of Wales.
Map of Great Britain.
Formation of "The King's Colours".
The Kings Colours.
Kingdom of Ireland
The Kingdom of Ireland.
St Patrick's Cross is also Red on a White background.
The United Kingdom of Great Britain and Ireland
Map of The United Kingdom and Ireland.
Formation of "The Union Flag".
The Union Flag.
The United Kingdom of Great Britain and Northern Ireland
Tragically Southern Ireland left the United Kingdom and formed a Republic.
Map of Great Britain and Northern Ireland.
St Patrick's Cross is taken to represent to Northern Ireland but in reality represents all Irish who emigrated to the United Kingdom and any British colonies. For instance 1/10 Brits have an Irish grandparent and Brits will never consider Ireland as a "foreign" country. It's even written into law:
Ireland Act 1949: "It is hereby declared that, notwithstanding that the Republic of Ireland is not part of His Majesty’s dominions, the Republic of Ireland is not a foreign country for the purposes of any law in force in any part of the United Kingdom or in any colony, protectorate or United Kingdom trust territory, whether by virtue of a rule of law or of an Act of Parliament or any other enactment or instrument whatsoever, whether passed or made before or after the passing of this Act, and references in any Act of Parliament, other enactment or instrument whatsoever, whether passed or made before or after the passing of this Act, to foreigners, aliens, foreign countries, and foreign or foreign-built ships or aircraft shall be construed accordingly." http://www.legislation.gov.uk/ukpga/Geo6/12-13-14/41
The Union Jack
The Union Flag was seen across the world incorporated into an Ensign which was hoisted onto the Jackstaff at the bow of a ship. It became known as The Union Jack.
The Red (Civil Merchant) Ensign
The White (Royal Naval) Ensign
The Blue Ensign
Strictly speaking the Union Flag was only called a Union Jack when present as an Ensign when hoisted onto a Jack Staff on the bow of a ship. The term Union Jack does not strictly apply to the land flag. However as a tribute of the Global impact of the British Navy, it is Globally renown as The Union Jack. Defaced Blue Ensigns became land flags for Australia and New Zealand while a Defaced Red Ensigns became the land flag of Canada.