Crusades, 14th and 15th Century
Two subsequent attempts were made to rescue the Christian states. The first, 1344 , in which Clement VI , the Hospitallers, the King of Cyprus, and the Venetians were prominent, involved numerous leaders and countries, and continued with very little success until 1400 . The second, also a fruitless effort, 1443 , after the Turkish Murad II had defeated the Greek emperor at Constantinople , 1422 , and the Council of Florence had proclaimed a religious union of East and West, 1439 , was brought to a close by the fall of Constantinople , 1453 .