 During the first stage of the family feud known as the Brothers' Quarrel, Ferdinand initially supported Rudolph II's brother, Matthias, who wanted to convince the melancholic Emperor to abdicate, but Matthias' concessions to the Protestants in Hungary, Austria and Bohemia outraged Ferdinand.He planned an alliance to strengthen the position of the Catholic Church in the Holy Roman Empire, but the Catholic princes established the Catholic League without his participation in 1610.Philip III of Spain, who was the childless Matthias' nephew, acknowledged Ferdinand's right to succeed Matthias in Bohemia and Hungary in exchange for territorial concessions in 1617.