In the Name of Allah, Most Gracious, Most Merciful
The Peace Treaty of al-Hasan, peace be on him, with Mu'awiya was among the most difficult problems from which the Imams of the members of the House (Ahl al-Bayt) suffered. This is because the Muslim community after Allah's Apostle, may Allah bless him and his family, criticized them very much.
Because of this Peace Treaty, al-Hasan, peace be on him, faced unbearable adversities. No one was able to bear those adversities but with the help of Allah, the Great and Almighty. Anyhow, al-Hasan bore them with patience to seek Allah's pleasure. He passed them successfully. For he wanted to be loyal to Allah, the Exalted, His Book, His Apostle, and all Muslims. So all his words and deeds were honest.
Those who have accused al-Hasan, peace be on him, of inclining to rest through his Peace Treaty with Mu'awiya are not important, nor are his Shi'a (followers). Enthusiasm has motivated them. Thus they said that al-Hasan should have fought against Mu'awiya. He had to reach life through the way of death. Besides he had to win victory and conquest in the way that his brother (al-Husayn) adopted at the Battle of Karbala', when he won a glorious victory and a clear conquest.
It is strange that the people have not understood the Peace Treaty of al-Hasan since then. In other words no one has explained his viewpoint with traditional and logical proofs. I (i.e., Sayyid Abd al-Husayn Sharaf al-Din) had tried to achieve this task. However, Allah, the Great and Almighty, had decreed to single out the author of this new book, namely 'Sulh al-Hasan,' to accomplish this task instead of me. In his book, the author has shown a sound judgment, detailed
correctness, and a separating limit between the truth and falsehood.
I (i.e., Sayyid Abd al-Husayn Sharaf al-Din) have studied the outstanding chapters of the book. So I have understood that they (the chapters) represent the outstanding merit of their noble, righteous author. For they are similar to each other in study, exactness, moderation, plain explanation, proof, floweriness, observation, the piety of quoting, good debates, and the appropriate comprehension of the subjects. Also they are similar to each other in the simple style, the logical coherence, the eloquent conciseness, and the accepted wordiness.
So the book has been controlled by an organizing, creative mind that is regarded as a proof. For, in it, the style matches comprehension, and clarity matches deep understanding. In other words these are the elements of analytic criticism.
As for the author, may Allah promote his rank, you can conclude his qualities from his abilities in this book. Although you have not seen the author, you can draw his picture when you read his features in this book. For it shows you that the author has a clear beginning. He has a bright face. He has sweet words, a good temper, good-heartedness, clemency, great mind, plentiful knowledge, many reports, art writings, good hints, and nice metonymies, and wonderful metaphors. Also this book shows you that wisdom manifests itself through his good words and deeds. You cannot find a person whose manners are better than his. The author has a lot of information about the sciences of the family of Muhammad, may Allah bless him and his family. He is a scholar and researcher. He has deeply studied the secrets of the family of Muhammad, may Allah bless him and his family. So he has discovered their secrets. Nothing has escaped him because of his outstanding qualities that his book represents clearly.
Whoever considers the contents of the book carefully, namely Mu'awiya's and al Hasan's conditions, knows that they (Mu'awiya and al-Hasan were two caliphs with two different manners. As for the manners of al-Hasan, they are the manners of the Qur'an and of the Sunnah (the Prophet's words and deeds). In other words they are the manners
manners of Mu'awiya, they are the manners of the Umayyads. Namely they were the manners of Abu Sufyan and of Hind.
Whoever wants to study in detail the history of the two families (the family of Muhammad and of Mu'awiya), will know their different manners.
When Islam came, Allah helped His Servant and Apostle to achieve that clear conquest and to win that glorious victory. So the Umayyad's wicked intentions disappeared.
Then Abu Sufyan, his sons, and his relatives were forced to surrender in order to spare their blood. For if they had not surrendered, their blood would have been shed. So they embraced Islam as the people did, while their hearts were full of malice. So they waited for an opportunity to carry out their wicked plans against Muhammad and his family. Though Allah's Apostle, may Allah bless him and his family, was acquainted with their attitude, he treated them kindly in order to reform them.
The Prophet's kind treatment towards Abu Sufyan, his son, and his relatives compelled them to hide their enmity towards him. That is because they were afraid of him and eager for money. So after the coming of Islam, the people were about to forget the Umayyads even in their narrow homeland, namely Mecca.
As for the battles of conquest after Allah's Apostle, may Allah bless him and his family, the people knew nothing about the Umayyads. They only knew that they belonged to the Prophet's family and his Companions.
Then, after the Prophet, some people, who did not belong to the Prophet's family, were able to take the reins of power. So under their shade, Mu'awiya became the greatest of all the governors in power, words, and deeds.
At that time Mu'awiya used his cleverness to make Islam a bridge to cross to power. to corrupt Allah's religion, to enslave His creatures, and to waste the Public treasury. Allah's Apostle told the Muslims about these deeds of Mu'awiya. These deeds occurred as the Prophet said. So they were among the signs of his Prophethood.
Mu'awiya became active during the time of the second and third Caliphs. For they made him a governor over Sham (Syria) for twenty years. So he was able to control the organs of government strongly. In the meantime he fed and bribed the people of Sham (Syria). So they were his supporters there. Accordingly, he was a danger against Islam. For the people knew that he was from Quraysh (the family of the Prophet, may Allah bless him and his family), and that he was among the Companions of the Prophet. These qualities made him more famous than the foremost Companions, such as Abu Dharr, 'Ammar, al-Miqdad, and the like with whom Allah was pleased, and who were pleased with Him.
In this manner the Umayyads came to power again. They began competing with the Hashimites using their name openly. Still they (the Umayyads) plotted against them secretly. They (the Umayyads) seized the opportunity to deceive the common people with their cunning. In the meantime they bought the prominent people. They showered them with the money that belonged to the common people. Also they gave them positions paying no attention to Allah's will. That is because Allah refused to give such positions to the traitors like them. They took advantage of the conditions of the conquest and the pleasure of the Caliphs with them.
When the Umayyads took the reins of power through Mu'awiya's cunning, they followed satanic methods to corrupt the religious commandments. For they wanted the Muslim community to lead the pre- Islamic lifestyle that was full of recklessness and atheism. To achieve their interests through such kind of lifestyle, the Umayyads adopted a pagan method and a utilitarian plan.
However, all people did not understand the pagan method and the utilitarian plan of the Umayyads. For they adopted an Islamic rule that says: "Islam abolishes what had been before it." Thus Islam concealed the atrocities of the Umayyads. Moreover, Allah's Apostle, may Allah bless him and his family, forgave them and treated them kindly. The Caliphs took them as close companions, made them governors over Muslims, and gave them powers of which no governor had. So the Umayyads applied their policy to Sham (Syria) for twenty years.
However, they did not refrain from committing ugly acts, nor did they prevent other people from doing them.
The Second Caliph (i.e., 'Umar) kept an eye on his governors. He punished them severely. For example, he punished Khalid b. (bin) al-Walid, who was his governor over Qansarin. When he heard that the latter gave al-Ash'ath ten thousand dirhams, he ordered Bilal al-Habashi to tie him with his turban. Then he (the Second Caliph) made Khalid stop before him on one leg and without a turban. He punished him before the political leaders and the prominent figures at al-Masjid al-Jami' in Hams. Then he began to ask him about the ten thousand dirhams and whether they belonged to the public treasury or to his own property. If the ten thousand dirhams had belonged to his own property, then it would have been an act of extravagance. For Allah does not love the extravagant. If the ten thousand dirhams had belonged to the public treasury, then it would have been an act of treason. For Allah does not love the traitors. Then the Second Caliph removed Khalid from office forever.
The Second Caliph summoned Abu Hurayra and said to him: "You know that I have made you a governor over Bahrain, while you had no sandals. Now, I have heard that you sold some horses for a thousand and six hundred dinars." Abu Hurayra said: "We had some horses and they reproduced. We received gifts one by one." The Second Caliph said: "I have fixed your livelihood and provisions. This is an addition. You should pay it." Abu Hurayra said: "This addition does not belong to you." The Second Caliph said: "Pay it; otherwise I will hurt your back." Then he (i.e., the Second Caliph) stood up and whipped Abu Hurayra on the head till he bled. Then he said: "Fetch it (i.e., the addition)." Abu Hurayra said: "Sacrifice it in anticipation of Allah's reward." The Second Caliph said: "That would be right if you took it (the addition) legally and paid it with obedience. Do you not know that the people collect money even from the remotest stone of Bahrain?. Does this money belong to you or does it belong to Allah and the people?"
In this connection Abu Hurayra said: "When 'Umar removed me from Bahrain, he said to me: 'Enemy of Allah and enemy of His Book,
you have stolen the money of Allah!' So I said: 'I am not the enemy of Allah, nor am I the enemy of His Book. Rather I am the enemy of your enemies. I have not stolen the money of Allah.' He ('Umar) said: 'From where have you brought this ten thousand dirhams?' So I (i.e., Abu Hurayra) said: 'Some horses reproduced, gifts came one by one, and shares came regularly.'" He (i.e., Abu Hurayra) said: "So he ('Umar) took it (the ten thousand dirhams) from me."
'Umar treated his governors as he treated Khalid b. al-Walid and Abu Hurayra. Those who have studied 'Umar's policy know his treatment towards his governors. For example, he dismissed Abu Musa al-Ash'ari, Quddama b. Maz'un, al-Harith b. Wahab, and one of the sons of Layth b. Bakr  after he had divided the money among them.
This was the policy of 'Umar towards his governors. In other words he treated them severely. However, Mu'awiya was his close companion though he was opposed to his policy. 'Umar did not prevent Mu'awiya from doing anything, nor did he punish him for doing ugly deeds. Rather he said to him: "I do not order you, nor do I prevent you." Besides he let him do according to his viewpoint.
This treatment of 'Umar made Mu'awiya a tyrant and encouraged
him to carry out his Umayyad plans. So al-Hasan and al-Husayn
were in danger because of Mu'awiya's cunning. Islam was also in
danger because he spared no effort to destroy it in the name of Islam
and to put out the light of the truth with the name of the truth.
Accordingly, to remove Mu'awiya's danger, al-Hasan and al-Husayn
were before two choices: either to resist Mu'awiya or to surrender to
him. As for the resistance under the leadership of al-Hasan, they
thought that it would certainly destroy those who protected the
religion and its followers. Also it would destroy those who guided
people to Allah, the Great and Almighty, and to His straight path. On
the other hand, his brother al-Husayn sacrificed his life at the Battle of
 Al-Zubayr b. Bakkar, al-Muwaffaqiyat. Concerning the biography of al Harith b. Wahab, b. Hajar has reported the above- mentioned words in his book 'al-Isaba,' Chapter One, on the authority of al-Zubayr b. Bakkar.
Karbala'. He gathered the Hashimites and their followers. He waged war against the strong Umayyads. If al-Hasan had sacrificed his life in this manner, the battle would have resulted in killing them all. 
Namely the Umayyads would have gained a victory over them and achieved their hopes and desires. If al-Hasan and his followers had been killed, the Umayyads would be the only rulers over the Muslim community. So al-Hasan, far be it from him, would fall into what he escaped from in the worst manner. Also his sacrifice would have no effect on the public opinion except blame and refute. 
From here al-Hasan, peace be on him, decided to leave Mu'awiya play with his tyranny and to test him with authority. However, al Hasan obligated Mu'awiya to conform to the Qur'an and the Sunna (the Prophet's words and acts). Also he obligated him not to punish the Shi'a for a certain mistake they had done towards the Umayyads, to respect them, and to give them their rights fully like the other Muslims. Besides al-Hasan obligated Mu'awiya to carry out other conditions though he knew that the latter would not fulfill his promise or would do the opposite. 
 As Shaykh Radi Al-Yasin has explained in this book.  That is because Mu'awiya insisted on making a peace- treaty with al Hasan. He declared that he was ready to carry out all conditions of al-Hasan for Allah and the community. He besought him to prevent the bloodshed of the community of his grandfather. He (Mu'awiya) declared his request, so the two parties knew it. If the battle had lasted, Mu'awiya would have defeated al-Hasan. Al-Hasan, Mu'awiya, and their soldiers knew the result of the battle. So if al-Hasan had insisted on fighting Mu'awiya he would have been defeated and blamed. Moreover, if al-Hasan had said that Mu'awiya would not fulfill his conditions, the common people would have not believed him because they admired Mu'awiya, as we have already mentioned, and because the defects of the Umayyads were not clear for them to support al-Hasan and to abandon Mu'awiya. However, the defects of the Umayyads during the lifetime of the Lord of martyrs (i.e., al-Husayn) were so clear that his sacrifice played an important role in supporting the truth and its followers, praise be to Allah. Read the chapter: "the Secret of the Attitude" in this book.  Read the Peace Treaty in this book.
Al-Hasan, peace be on him, made these conditions to show the people the artificial qualities of the Umayyads and to show them the false aspects of Mu'awiya. In other words al-Hasan wanted to show the people that Mu'awiya and the Umayyads were ignorant, far away from the true Islam, and full of spites. Though Islam treated them (the Umayyads) kindly, they remembered their defeats at the battles of Badr, 'Uhud, and al-Ahzab (the allies).
Generally speaking, al-Hasan planned to create a stormy revolution through that necessary Peace Treaty. He made peace with Mu'awiya because of his critical circumstances: the people at that time were not able to distinguish between right and wrong, and the tyrants strongly controlled authority.
Al-Hasan, peace be on him, did not start this plan, nor did he end it. Rather he took it from his grandfather, and then his grandsons adopted it. He, like the other Imams, wanted to guide the people through his deeds. Allah tested him with this plan. So he (al-Hasan) yielded to it patiently to obtain Allah's pleasure. Then he passed the Divine test successfully.
Al-Hasan, peace be on him, learned this plan from the peace treaty of al-Hudaybiya. Namely, he learned it from the policy of his grandfather (Prophet Muhammad), may Allah bless him and his family. In other words he followed the good example of his grandfather. Still some of his prominent companions and followers criticized him for the Peace Treaty he made with Mu'awiya. However, he (al-Hasan) was indifferent to their blame.
Al-Hasan, peace be on him, made this plan (Peace Treaty). He wanted it to be an example for his brother al-Husayn, the Lord of the youth of Paradise, and the nine Imams after him. So the nine Imams based their wise policy on al-Hasan's successful plan during their critical conditions. Accordingly, al-Hasan's plan was a part of the Hashimite policy. He and the other Imams adopted it to support the truth, not to win victory for their own selves.
This Peace Treaty paved the way for al-Hasan, peace be on him, to ambush Mu'awiya through his own soldiers and to kill him while he did not know. Also the Peace Treaty helped al-Hasan to turn the
victory of the Umayyads into a mutiny against them.
Immediately after the Peace Treaty, the signs of the mutiny against Mu'awiya started. For example, the Iraqis rebelled against him. So he addressed them, saying: "Iraqis, by Allah, I have not fought against you to make you pray, nor to fast, nor to pay alms (zakat) nor to perform the hajj. Rather I have fought against you to be a ruler over you. Allah has given me that (authority), while you are reluctant to (it). I have put the Peace Treaty with al-Hasan b. 'Ali under my two feet."
When the people pledged allegiance to Mu'awiya, he delivered a speech. During his speech, he mentioned Imam 'Ali and al-Hasan to defame them. So al-Husayn rose to reply. However, al-Hasan said to al-Husayn: "Brother, slowly!" Then al-Hasan, peace be on him, stood up and spoke: "You who mentioned 'Ali, I am al-Hasan and 'Ali was my father. You are Mu'awiya and your father was Sakhr. My mother was Fatima and your mother was Hind. My grandfather was Allah's Apostle and your grandfather was Harb. My grandmother was Khadija and your grandmother was Futayla. May Allah curse him who is inferior to us in fame and ancestry, and who is the oldest one in evil, unbelief, and hypocrisy." So some groups of those who were present in the mosque said: "Amen!"
Then Mu'awiya adopted a certain policy to oppose the Qur'an and the Sunna (the Prophet's practice). For example, he did not prevent people from doing evil deeds. He killed the righteous, disgraced the good ones, stole money, imprisoned the noble, and made the reformers homeless. Moreover, he supported the corrupt persons and made them his ministers such as b. al-'As, b. Shu'ba, b. Said, b. Artat, b. Jundub, b. al-Samt, b. al-Hakam, b. Marjana, b. 'Aqaba, and b. Sumayya. It is worth mentioning that Mu'awiya separated b. Sumayya from his legitimate father. So b. Sumayya became Mu'awiya's brother. Then Mu'awiya appointed b. Sumayya a governor over the Shi'a in Iraq. He (i.e., b. Sumayya) killed their children, enslaved their women, sowed division among them, burnt their houses, and stole their money. Generally speaking, he did his best to persecute them.
Mu'awiya ended off his abominable acts with appointing his
corrupt son Yazid a ruler over Muslims. Yazid the corrupt spared no effort to destroy the religion of Muslims and to spoil their life in this world. For example, he killed al-Husayn, peace be on him, and his companions at the Battle of Karbala'. At the Battle of al-Hurra, he ordered Muslim b. 'Aqaba to ravage Medina for three days. Moreover, he ordered the commander of his army to use mangonels to throw fires and stones at Mecca.
This was the end of the deeds of Mu'awiya. This end was quite appropriate for the beginning of his black acts.
Between the beginning and the end, adversities doubled, misfortunes occurred, and ordeals overcrowded. I (Sayyid Abd al Husayn Sharaf al-Din) do not know how that time contained such adversities, misfortunes, and ordeals. I do not know how that society endured them. For if they were distributed throughout a time, the time would not contain them. If they were distributed all over a world, the world would become an unbearable inferno.
However, the events occurred to explain al-Hasan's plan. They showed the people that the Umayyads were wicked. Also they showed them that al-Hasan wanted to prevent the Umayyads from destroying the message of his grandfather.
Al-Hasan, peace be on him, was able to disclose the evil intentions of the Umayyads with his plan. So the Umayyads were overthrown, praise be to Allah.
With his plan, al-Hasan paved the way to his brother al-Husayn, the Lord of martyrs. So al-Husayn was able to declare his revolution with which Allah has explained in the Qur'an and made it a lesson for the wise.
Al-Hasan and al-Husayn, peace be on them, were two faces of the message. In other words they had equal attitudes towards it.
Al-Hasan was ready to grant his life for Allah. Al-Husayn was not more generous than al-Hasan in granting life for Allah. However, al Hasan kept his life to lead a silent struggle. When the time came, al Husayn died a martyr at the Battle of Karbala'. However, this martyrdom had belonged to al-Hasan before it belonged to al Husayn.
The wise deeply know that the sacrifice at the Battle of Sabat was more meaningful than that at the Battle of Karbala'. For al-Hasan, peace be on him, practiced bravery patiently. In other words he endured hardships in a peaceful way.
The martyrdom at the Battle of Karbalah belonged to al-Hasan, and then it belonged to al-Husayn. That is because al-Hasan had ripened its results and paved the way to it.
The bloody victory of al-Hasan depended on the truth which he clarified for his brother al-Husayn with his patience and wisdom. So when this truth became clear, al-Husayn won a victory over his enemies.
It is as if that al-Hasan and al-Husayn, peace be on them, were in agreement on the design of the plan. Namely, al-Hasan took the role of the patient, wise person, while al-Husayn took the role of the generous revolutionist. So they helped each other to make a perfect plan with one purpose.
After the Battles of Karbala' and Sabat, the people began to consider the events carefully. So they concluded that the Umayyads were an abominable, ignorant group. Also they concluded that the Umayyads played the most dangerous role to destroy Islam and Muslims. For they (the Umayyads) were full of malice.
The people understood that the Umayyads shared the same wicked nature, and that Islam was unable to educate such a kind of nature with its kind treatment. For example, Hind made a plan to kill Hamza (the Prophet's uncle). When Hamza was killed, Hind came to him, ripped open his chest, and began eating his liver. At the Battle of Karbala', Yazid gathered his fighters to attack al-Husayn and his companions. When al-Husayn was killed, Yazid ordered his fighters to break al Husayn's chest with the hooves of their horses. Besides he ordered them to cut off his head, and to leave him naked in the open air to be eaten by the birds and the beasts of prey. Moreover, Yazid ordered his fighters to take the prophet's granddaughters as prisoners.
The people knew that Mu'awiya went on his wicked plan towards al-Hasan till he poisoned him. They knew that Mu'awiya was
indifferent to the Peace Treaty, which he made with al-Hasan. Also they knew that al-Husayn revolted against the Umayyads because their oppression reached its zenith.
Accordingly, it was natural for the people to consider those events carefully. They wanted to know why the Umayyads deviated from the family of Muhammad, may Allah bless him and his family. They also wanted to know why that cunning, oppressive, Umayyad regime took the reins of authority. Moreover, they wanted to know why such a regime spared no effort to put out the light of the family of Muhammad or to prevent it from reaching the community.
Yes, the people knew the wicked plan of the Umayyads because of al-Hasan's and al-Husayn's efforts and their wise plan.
The people knew that there was a strong enmity between Islam and the Umayyads. We said that the Umayyads took the reins of authority through Mu'awiya and his Peace Treaty with al-Hasan. Then, why did Mu'awiya persecute al-Hasan and poison him? Why did he do his best to put an end to the righteous followers of al-Hasan?
Also Yazid killed al-Husayn and took the reins of authority, but why did he kill al-Husayn's followers mercilessly?
Indeed, we must leave the good ones who are acquainted with the Islamic history to discover the reality of the struggle between the family of the Prophet and the Umayyads. That is because we have detailed this matter in the introduction of the book: 'Al-Majalis alFakhira fi Ma'atim al-'Ittra al-Tahira'. See this book. Now, it is enough for me to mention that al-Hasan and al-Husayn helped each other to show people the real face of the Umayyads. So I want to underline this fact again: The martyrdom at the Battle of Karbala' belonged to al-Hasan first, and then it belonged to al-Husayn. The wise deeply know that the sacrifice at the Battle of Sabat was more meaningful than that at the Battle of Karbala'.
Thanks to our master, our prototype, the prominent figure of the community, expert in the secrets of the Imams, Hujjat al-Islam and Muslims, our holy Shaykh, Shaykh Radi Al-Yasin, may Allah promote his rank. For he was the first to discover the secret of the
relationship between the Peace Treaty of al-Hasan and the revolution of al-Husayn.
Besides, we must acknowledge that no one of the great figures devoted himself to this task as Shaykh Radi Al-Yasin did in this valuable book. So may Allah reward him and dwell him in the highest Heaven: "with those upon whom Allah has bestowed favors from the prophets and the truthful and the martyrs and the good, and a considerable company are they!"