Short answers, pulled from the story.
The First English Civil War began on the 22nd of August 1642 when King Charles I raised his royal standard at Nottingham. The conflict concluded with the Battle of Worcester on the 3rd of September 1651, which ended the Third Civil War.
King Charles I commanded the Royalist forces while Parliament appointed Robert Devereux third Earl of Essex as commander initially. Oliver Cromwell later led the disciplined New Model Army alongside Thomas Fairfax to defeat the Royalists.
Conservative estimates indicate roughly one hundred thousand people died from war-related disease in England and at least sixty thousand in Scotland. Total casualties including combat deaths and prisoners amount to approximately three point seven percent of the total population in England and six percent in Scotland.
The execution of Charles I established the Commonwealth of England as a republican government ruling from 1649 to 1653 and 1659 to 1660. It also altered dynamics in Scotland where Royalists and Covenanters raged between 1644 and 1650 before the Restoration.
The Third Civil War ended on the 3rd of September 1651 with the Battle of Worcester. The monarchy was restored when Charles II returned to London on the 29th of May 1660 following his Declaration Breda signed on the 4th of April 1660.