Most of us believe that England, Scotland, and Wales were united and became Great Britain in the 18th century, but surprisingly, this wasn’t the first time these lands were united under a single ruler. All the way back in the dark ages of the 10th century, an English king named Aethelstan managed to pull the three territories together, and the process started on July 12, 927.
Aethelstan was the son of Edward the Elder and the grandson of Alfred the Great, who managed to hold off Viking attacks against southern England. During his reign, Edward captured the eastern Midlands and East Anglia from the Vikings, and also claimed the kingdom of Mercia through his sister, who had married the late king. When Aethelstan came to the throne, he already had a considerable territory, but he wanted more.
He started out by making at least one strategic alliance by marrying his sister to the Viking king of Northumbria, who thankfully died just about the time he started to get troublesome. Aethelstan used the death to seize most of Northumbria, bringing England under the rule of a single king for the first time. He turned his attention to Wales, and the Welsh kings submitted to him at Hereford, though some remained opposed to his rule.
One of the few remaining opponents was Constantine II, King of the Scots, with whom Aethelstan went to war in 927. The two monarchs agreed to a meeting at Eamont Bridge on July 12 and reached an agreement whereby Constantine and his supporters would not ally with the Viking kings. This is viewed as the real beginning of the unification of Great Britain (for the first time, at least).
Despite the agreement (and the fact that Aethelstan stood godfather to one of Constantine’s sons), relations between the two kings remained frosty, and Aethelstan once again marched on Constantine in 934. It’s unclear what happened after that (some say there was a battle, others claim there was no opposition), but Aethelstan returned south with one of Constantine’s sons as a hostage, and Constantine himself came along for the ride. Constantine recognized Aethelstan as his overlord in September of that year, putting Scotland in Aethelstan’s hands.
Aethelstan died at Malmesbury on October 27, 939 and was succeeded by his 18-year-old half brother, Edmund. His empire collapsed in little more than a year following a Viking attack. Still, Aethelstan is generally viewed as the first king of England, and his reign was the first time the kingdoms of England, Wales, and Scotland were united under one ruler.