The Commonwealth Of England Was The Official Name Of The Political Unit

The Commonwealth of England was the official name of the political unit (de facto military rule in the name of parliamentary supremacy) that replaced the Kingdom of England....
(after the English Civil War) from 1649–53 and 1659–60, under the rule of Oliver Cromwell and his son and successor Richard. From 1653 to 1659, although still legally known as a Commonwealth, the republic,

 united with the former Kingdom of Scotland, operated under different institutions (at times as a de facto monarchy) and is known by historians as the Protectorate. In a British context, it is sometimes referred to as the "Old Commonwealth"