The Sherley brothers' mission in Iran dealt with some aspects. They carried a message from England and the Christian world to Shah Abbas. In addition, they trained Iranian army and taught them how to make artillery, they fought with the Iranians against the Ottoman Empire shoulder to shoulder and both of them were sent to Europe for political and commercial purposes by Shah Abbas. Shah Abbas sent the brothers with the intention of making the west frontier active against the Ottoman Empire. Anthony Sherley was sent to Europe once and not getting any result, he didn’t come back to Iran. Moreover Robert Sherley, his younger brother, who was respectfully held as a hostage in Iran, was sent to Europe twice, owing to the fact that Shah Abbas liked him and utterly trusted him. Although the Sherley brothers couldn’t yield much result during their mission, the mission facilitated political relationships of Iran and Europe and made closer ties, especially by including the fact that their mission was not limited to any special country, that they paid particular attention to powerful governments and also the fact that the Pope was taken into consideration. Their presence in the scope of political relationships, definitely, was not irrelevant to the Pope and the Christian priests' prior intentions. Such missions made the priests partly jealous of the Sherley brothers. Meanwhile, it also made the priests partly happy with them. On the one hand Carmelites supported the Sherley brothers and in particular Robert whose wife, Treza, was baptized by them. On the other hand, the Portuguese Augustinian priests noticed the effective presence of the Sherley brothers against the Portuguese and Spanish national interests especially by taking the fact that Shah Abbas succeeded in deporting the Portuguese from south of Iran and Hormoz with the help of the British.