Britannia was the common Latin name for the island of Great Britain starting in the 1st century BC. Britannia replaced the name Albion as the Romans' common name for the island. After the Romans overcame the ancient Britons in war in 43 AD, Britannia could mean just the southern two thirds of the island which was under Roman control. (Caledonia, north of the River Forth in modern Scotland, was only sometimes controlled by the Roman army.)