When we want to study the march of Imam Hussein (A.S), we have to take it as a whole. We have to study it, he made peace as well as when he make war. In both cases, he was a revolutionary. To engage in a revolution does not mean only fighting in a direct way. You might fight with when you hold your sword in your hand, as well as when it is on your side. In many cases, you might fight by preparing the circumstances, and the base that could face the challenges. Such a war might be more effective in the beginning than resorting to arms.
A war by means of peace:
How did Imam Hussein start his war through Imam Hassan's peace. They both made a truce with Muawiyah, because the army was exhausted, and the people were unaware of the real picture, as a result of the wars from the beginning of Ali's caliphate until his martyrdom, which veiled the deviated rule of the Umayyad rule.
People lacked a clear vision. Wars usually make people preoccupied with what is going on-especially when one of the parties is victorious. Moreover, the fighters were tried and they were not enthusiastic to go to war. The tribal leaders benefited from this exhaustion and were able to convert it to benefit its own interests. The war in these circumstances represented a loss for the cause and not only for the person.
Imam Al- Hassan wanted to give the people a chance to experience the rule of the Umayyads, and learn how deviated they were. The revolution would then be a natural reaction that people will reach as a result of their own experience.
And this what happened, and people began to learn the type of class discrimination, partisanship and fanaticism the Umayyad rule represented, especially how they used to employ their own people and leave the others no matter how qualified they were.
Then in the end, Muawiyah who promised Imam Hassan (A.S) to be the caliph after him, conspired and poisoned the Imam (A.S). When the Imam (A.S) was martyred, Muawiyah wanted to force the people to pledge loyalty to his son, Yazid. A man stood carrying bags of money in one hand and a sword in the other had saying: Who pledges the loyalty will have this (pointing to the money) and who refuses will have that (pointing to this sword).
Such tyranny aggravated, and the honourable companion, Hujr bin Udai was killed along, with his son and some of his followers, because he refused to renounce Imam Ali.
Then, cursing Imam Ali was passed as a law in all Friday prayers and Eids and in all parts of the Islamic state.
Favourable conditions:
This rule of tyranny aggravated until people could no longer tolerate it, and revolution became a natural reaction that everybody was talking about.
Then, the whole situation was further aggravated, when Muawiyah asked the people to pledge their loyalty to his son, Yazid.
Imam Hussein (A.S) stood up in a decisive stand that gave the issue its significant size and said: we are the family of prophethood whom the Qur’an was revealed to, while Yazid is a dissolute man who drinks wine and kills innocent people despite Allah's prohibition. And ended by saying: A man like me does not pledge loyalty to a man like him.
Revolution on Tyranny
Thus, Imam Hussein declared his opposition to the tyrant rule. Then he started to prepare the psychological atmosphere for leaving Al-Medina. He chose to leave the people before the ninth of Zil-Hijja while the pilgrims were on their way to Mina. He transformed his Hajj into an Umra and left the people who were waiting for the Imam to be with them on the Mount of Arafa. The people were heading for Mina while he was heading for Iraq.
Why did the Imam take such a step?
He wanted the people to wonder about why he did not leave straight to Iraq from Mecca, but left the day the people were getting ready to stand at Arafa, to initiate a revolution against Yazid and the Umayyad rule.
He also left in an interesting way. Usually a rebel would not take with him his family and children and those of his, but the Imam did just that to create a feeling of protest in the eyes of everyone who saw the convoy making the people feel that even the Imam's family and children were threatened by the tyrant ruler, and that it would not be safe to leave them in Medina, the continuation of the revolution after his Martyrdom.
source : tebyan