Charles I, Wentworth had them imprisoned. However, settlement proceeded only in County Sligo and County Roscommon. Next, Wentworth surveyed the major Catholic landowners in Leinster for similar treatment, including members of the powerful Butler dynasty. Wentworth's plans were interrupted by the outbreak of the Bishops Wars in Scotland, which eventually resulted in Wentworth's execution by the English Parliament and civil war in England and Ireland. Wentworth's constant questioning of Catholic land titles was one of the major causes of the 1641 Rebellion, and the principal reason why it was joined by Ireland's wealthiest and most powerful Catholic families. The 1641 Rebellion In October 1641, after a bad harvest and in a threatening political climate, Phelim O'Neill launched a rebellion, hoping to rectify various grievances of Irish Catholic landowners. However, once the rebellion was underway, the resentment of the native Irish in Ulster boiled over into indiscriminate attacks on the settler population in the Irish Rebellion of 1641. Irish Catholics attacked the plantations all around the country, but especially in Ulster. English writers at the time put the Protestant victims at over 100,000. William Petty, in his survey of the 1650s, estimated the death toll at around 30,000. More recent research, however, based on close examination of the depositions of the Protestant refugees collected in 1642, suggests a figure of 4,000 settlers were killed directly; and up to 12,000 may have died of causes also related to disease (always a cause of high fatalities during wartime) or privation after being expelled from their homes. Ulster was worst hit by the wars, with massive loss of civilian life and mass displacement of people. The atrocities committed by both sides further poisoned the relationship between the settler and native communities in the province. Although peace was eventually restored to Ulster, the wounds opened in the plantation and civil war years were very slow to heal and arguably still fester in Northern Ireland in the early 21st century. In the 1641 Rebellion, the Munster Plantation was temporarily destroyed, just as it had been during the Nine Years' War. Ten years of warfare took place in Munster between the planters and their descendants and the native Irish Catholics. But the ethnic/religious divisions were less stark in Munster than in Ulster. Some of the earlier English Planters in Munster had been Roman Catholics and their descendants largely sided with the Irish in the 1640s. Conversely, some