In the 1370s, the aged King Edward III of England left the governance of the realm in the hands of his third surviving son, John of Gaunt, 1st Duke of Lancaster. While Lancaster acted as de facto king of England, he brought together a group of powerful men whose unwavering loyalty was critical in the duke’s scheme to seize the realm. The insatiable appetite of John of Gaunt extended as far as coveting the authority of the church and centralizing that power under the crown. Lancaster’s web of supporters propagated his agenda in the governance of the kingdom, and threw the church in England into an age of turmoil and uncertainty, leaving it vulnerable to possible appropriation by the temporal realm. John of Gaunt's grandson, King Henry V, adopted Lancaster’s flawed tactics for constructing a power base, and improved them. Examining the political maneuvering of John of Gaunt, Duke of Lancaster and his grandson, King Henry V, this book will show how the House of Lancaster wove the authority of both the temporal and spiritual realms into an inescapable web that enabled John of Gaunt’s direct descendents to secure their continuous position as heirs to the throne of England.