As a result of the outbreak of the English Civil War in 1642, no English troops were available to put down the uprising and the rebels were left in control of most of Ireland. The Catholic majority briefly ruled the country as Confederate Ireland (1642–1649) during the subsequent Wars of the Three Kingdoms in Britain and Ireland. The Confederate regime allied themselves with Charles I and the English Royalists, though they did not sign a formal treaty with them until 1649. Had the Royalists won the English Civil War, the result could have been an autonomous Catholic ruled Ireland. However, the Royalists were defeated by the Parliamentarians, Charles I was executed and Oliver Cromwell re-conquered Ireland in 1649–1653 on behalf of the English Commonwealth. The Cromwellian conquest of Ireland was marked by atrocities, such as the massacre of the Royalist garrison at the Siege of Drogheda in 1649. Another policy implemented by the Cromwellian regime was the deportation of prisoners of war to the West Indies. Even worse was a scorched earth policy carried out by Parliamentarian commanders to subdue Irish guerrilla fighters, which caused famine throughout the country.