This book is about the transformation of England’s trade and government finances in the mid-seventeenth century, a revolution that destroyed Ireland. During the English Civil War a small group of merchants quickly achieved an iron grip over England’s trade, dictated key policies for Ireland and the colonies, and financed parliament’s war against Charles I. These merchants were the Adventurers for Irish land, who, in 1642, raised £250,000 to send a conquering army to Ireland but sent it instead to fight for parliament in England. The Adventurers elected a committee to represent their interests that met in secret at Grocers’ Hall in London, 1642–60. During that time, while amassing enormous wealth and power, the Adventurers laid the foundations for England’s empire and modern fiscal state. Although they supported Cromwell’s military campaigns, the leading Adventurers rejected his Protectorate in a dispute over their Irish land entitlements and eventually helped to restore the monarchy. Charles II rewarded the Adventurers with one million confiscated Irish acres, despite their role in deposing his father. This book explains this great paradox in Irish history for the first time and examines the background and relentless rise of the Adventurers, the remarkable scope of their trading empires and their profound political influence. It is the first book to recognise the centrality of Ireland to the Wars of the Three Kingdoms.