Consider a sect, whom despite its truth, is put under pressure by the government and other political and religious groups. They are slaughtered in the open and in secret, never leaving them a decade in peace, and the government to maintain its hatred and animosity tricks the society, well despite its desire to be kind to this group. Considering the vast territory of the government, the story gets even worse by going farther away from the residence of the Imam of this group.
In the midst of such conditions, the Imam of this sect must on one hand preach religion, a duty placed upon him by Allah (SWT) and handed to him by the Holy Prophet (S.A.W.), to meet the spiritual needs of society; and on the other hand must defend the lives, properties, and faith of his current followers who are under a great deal of pressure and surveillance. The Caliph views this group as his major political competitors, and thus places them in prisons when killing is not possible. Likewise, the scholars of other sects consider them as their theological rivals, and fear this sect's popularity amongst their own followers.
Over time, with the wise efforts of the Infallible Imams (A.S.) and their companions, the boundary of Shiite society moved out of the city of Kufa into different places of the Islamic state. After the migration of Imam Reza(A.S.) to Khurasan, his family members were forced out and scattered throughout the country as opposition towards them increased. Many Shiites (1) moved to eastern provinces of the country and often lived in communities far from each other. This was a major step in the migration and development of Shiite society.
There however remained a communication problem with the expansion process.(2) There was now a need for a systematic means of communication with the Imam, who leads and guides the whole society, as well as a means to correspond between the Shiites themselves. This matter came to more of an importance during the time of the ninth Holy Imam, Imam al-Jawad(A.S.), which led to the establishment of a system of deputies. Within this system, the Imam would select each deputy, whom would then deliver the Imam's guidance on religion and politics to the people within their region. This system had a hierarchical form and covered various geographical areas. The deputies were grouped under a higher ranked deputy, who would be responsible for all contacts above him, until it would finally reach the Imam himself.
During the lifetime of Imam Hasan al-Askari(A.S.), despite Abbasid Dynasty's close watch on him, the Imam had managed to maintain communication with the people through this very system of deputies. He would appoint persons with bright knowledgeable backgrounds as his deputies. They were selected from those people who had strong ties with the previous Imams, or with himself, and whose academic reputation could be a firm support for the Shiites.
By contemplating different letters and sayings of Imam Askari(A.S.) one can find these letters had a great role in guidance of Shiites on performing their religious rituals, and on recognition of the Imam's deputies. Through these letters, Imam Askari(A.S.) would emphasize his deputies' accountability, while also distinguishing and clarifying their positions and locations. With this, he strengthened trust toward his deputies amongst the Shiite community and even when certain doubts and accusations were made towards a deputy, the Imam would reply back in another letter to clarify the doubts.
Of the noticeable and educative features of this system, there comes the debate of traitorous deputies, and how they were dealt with through such system. In rare incidents, when a deputy from amongst all others would fail to fight his desires, and as a result steal from Shiite properties (3), the Imam would write a letter admonishing and removing that person (whom was chosen in the first place because of his faith and obedience to Allah's (SWT) laws to be a connection between the people and the Imam) from his position. Such a person would be banished immediately from the Shiite community, and as a result free the Shiite community from any further dangers carried out by such person.
Another great application of this deputy system was to avoid penetration of false groups such as people who did not believe in the twelve Imams, Ghulaat (4) and other forged Shiite sects. This system was especially very important to maintain the rich culture of Shia, and avoid vicious thoughts brought by the enemy to affect those living further away from the Imam. Moreover, this system (as it was started at the time of earlier Imams) provided a foundation for the occultation era of the last Holy Imam, Imam al-Mahdi(A.S.). Such a connection allowed the Shiite community to preserve its culture and eventually maintain its right thoughts from the wrong ideas of other sects. Furthermore, the usage of such accurate system allowed Shiite teachings to spread in smaller communities. Lastly, the major means of communication were through letters, a process most advanced in its time.
Reference: "The Political and Theological life of Shiite Imams(A.S.)" by Rasool Ja'farian Footnotes:
1- Despite the pressures exerted by the Abbasids, the lovers of Ahl al-Bayt(A.S.) had increased. Here by mentioning Shiite we mean the real followers of Ahl al-Bayt(A.S.) and not the lovers of Ahl al-Bayt(A.S.). Imam Hassan al-Askari(A.S.) has explained the difference between Shia and lover of Ahl al-Bayt(A.S.) in a narration. (Tafsir Imam al-Askari (A.S.) p. 316) 2- Some Shiite centers at the time of Imam al-Askari(A.S.) were: Kufah, Baghdad, Neyshabur, Qum, Aabeh, Mada'in, Khurasan, Yemen, Rey, Adhrabayjan, Samara, Jorjan, Basrah.
3- These expenses had a critical role in defending the Shiites, strengthening the needy Shiites and the oppressed people. 4- Ghulaat were people who tried to exaggerate the position of the Imams (A.S.) to carry out their own evil plans. In some cases they introduced the Imams(A.S.) as the Lord and in some other cases would claim to be the deputy of the Imam(A.S.). The Infallible Imams would severely struggle with these people.