Walsingham, Elizabeth's spymaster had established the most extensive spy network the world had ever seen, placing secret agents throughout Europe, especially in the Catholic courts of Spain, Italy, and France, to ferret out Catholic plots against Elizabeth. He took an active part in the persecution of Catholics and, with the backing of William Cecil, entered Parliament in 1563. Joining the Privy Council in 1573, he was knighted in 1577. The ousted Catholics championed Mary Queen Scots. Fearful of an uprising, Elizabeth offered Mary sanctuary against the Scottish reformers and then betrayed and imprisoned her. She then plotted with Walsingham to compromise Mary. Through his talented spies Walsingham built a case against Mary through her letters - which are suspected now to have been forged by Walsingham himself - and which eventually brought about a death warrant for Mary from Elizabeth. He later discovered information about the attack of the Spanish Armada - which was sent by an outraged King Philip of Spain who accused Elizabeth of regicide. Yet in later years, Elizabeth all but ignored her spymaster. Walsingham, distrusted for being too powerful and having information that might.