Britannia was the term used by the Romans to refer to the Roman province covering much of the island of Great Britain. At the height of Roman Britain, the Empire included most of the island of Great Britain.
The Romans built Hadrian's Wall close to today's border between England and Scotland. The province was named Britannia, and the unincorporated area of northern Britain was called Caledonia.

A Celtic goddess called Brigid is one of the many sources of the personification of Britain, but Britannia remained a place, not a female personification of the land, until she appeared on coins issued under Hadrian, which introduced a female figure labelled BRITANNIA.

Britannia was soon personified as a goddess. Early portraits of the goddess depict Britannia as a beautiful young woman, wearing the helmet of a centurion, and wrapped in a white garment. She is usually shown seated on a rock, holding a spear, and with a spiked shield propped beside her. Sometimes she holds a standard and leans on the shield.

With the constitutional unification of England with Scotland in 1707 and then with Ireland in 1800, Britannia became an increasingly important symbol and a strong rallying point among Britons.

British power, which depended on a liberal political system and the supremacy of the navy, lent these attributes to the image of Britannia. By the time of Queen Victoria, Britannia had been renewed. Still depicted as a young woman with brown or golden hair, she kept her Corinthian helmet and her white robes, but now she held Poseidon's three-pronged trident and often stood in the ocean, representing British naval power. She also usually held or stood beside a Greek hoplite shield, which sported the British Union Flag. Also at her feet was often the British Lion, an animal found on the arms of England, Scotland and the Prince of Wales.

Perhaps the best analogy is that Britannia is to the United Kingdom and the British Empire what Marianne is to France or perhaps what Columbia is to the United States of America. Like Columbia, Britannia became a very potent and more common figure in times of war and represented British liberties and democracy.