The English Civil War was a period of conflicts waged over control of England, Scotland, and Ireland in the mid-1600s. The events of the English Civil War were incredibly complex, and ended in the execution of Charles I of England, and the installation of the Commonwealth of England, a government which controlled England for almost 12 years before the British Monarchy was restored.

Charles I of England laid the groundwork for the Civil War early in his career. He was struggling to govern England, Ireland, and Scotland, and he made the profound mistake of trying to treat these territories like a single entity, raising ire in many parts of his kingdom. Charles also became engaged in conflicts in Europe, leading to unrest among members of Parliament. During this period in British history, the Parliament was weak, held only when the Monarch needed funds or other forms of support. As a result, when Charles I called a parliament into session to raise funds to pay for his involvement in Europe, the members only complained bitterly about the problems they saw in the government, leading the King to dissolve the Parliament in 1628. He did not call another Parliament for 12 years.

In the 1630s, Charles I attempted to institute religious reforms in Scotland, and he was soundly rebuffed. Scottish and English forces battled along the Scottish border, and Charles I was running out of money, leading him to call a Parliament again in 1640. This Parliament again spoke in opposition to the Monarchy, and Charles I dissolved it shortly after it was formed, leading to the nickname “The Short Parliament.” Under immense financial and political pressure, the King established yet another Parliament, and two years later, England, Ireland, and Scotland had descended into chaos, and the first English Civil War began.

Supporters of the King were known as Royalists or Cavaliers, and Parliamentarians were called Roundheads, after their severely cropped hairstyles. During the First and Second English Civil Wars, these factions fought bitterly for control of England and Scotland, and a number of political intrigues complicated matters even further. In 1648, these conflicts culminated with a rash of executions and a trial of the King for treason; he was executed in 1649.

After the King's execution, England experienced a Third Civil War, which ended with the establishment of the Commonwealth. England was essentially ruled by Oliver Cromwell, a major leader in the English Civil War, from 1653 to 1658, and his son took over to rule briefly before Charles II was brought back from exile in Europe and restored as the King of England. Charles II had learned his lesson from the English Civil War, and the government took the form of a parliamentary monarchy when it was reestablished in 1661.