Roman empire fell leaving many small kingdoms to arise. Over time, one kingdom, Wessex, grew stronger than the others and conquered the other kingdoms. Wessex unified forming England into a single nation in the 1800s.
Step-by-step explanation:
In the early 1700s, England then unifies with Scotland, Wales, and Northern Ireland to form Great Britain.
In 1707 ,the United Kingdom of Great Britain came into being as the results of Acts of Union being passed by parliaments of England and Scotland to ratify the 1706 Treaty of Union and to unite the two kingdoms.