The war ended in the battle of Karydi in May/June 1258, where William defeated the Duke of Athens, Guy I de la Roche, who had allied himself with the rebellious triarchs.
A guerra terminou na batalla de Karydi en maio/xuño de 1258, onde Guillerme derrotou ao duque de Atenas, Guido I de la Roche, que se aliou cos triarcas rebeldes.