Islam's History - , The Battle of Islam at Nahrawan:

After the unsatisfactory conclusion to the Battle of Siffin , Imam Ali
(A.S.) returned with his army back to Kufa on the 13th of Safar 37
A.H. During the march, a group of 12,000 men kept themselves at a
distance from the main part of thearmy.
The group was furious at the way things had ended at Siffin. These
were the Kharjites (Kharjite means one who rebels against religion).
They were the same people who had put down their weapons on the
battlefield. Now they said that Imam Ali (A.S.) had betrayed Islam by
agreeing to the truce andshould have referred judgment to the Holy
Qur'an alone or continued to fight. They demanded that he repentfor
this great sin.
When the army neared Kufa, the Kharjites camped at a village named
Harura. They started saying that all Muslims were equal and nobody
could rule over the other. In this way, they denounced both Imam Ali
(A.S.) and Muawiya and said that their belief was in "La Hukma Illa
Lillah", meaning, "No Ruler ship except by Allah alone."
Imam Ali (A.S.) sent Sasaa Bin Sauhan and Ziad Bin Nazr Harisi in the
company of Ibne Abbas towards them and afterwards himself went to the
place of their stay and tried to explain to them that they were
misunderstanding the words "La Hukma Illa Lillah" , and that in
accepting the arbitration (peace talks) at Siffin, he had not gone
against theteachings of the Holy Qur'an.
He pointed out that they themselves were at fault, because they should
never have laid down their arms and forced him to call back Malike
Ashtar , who was at the point of securing victory. He reminded them
that they had pressed for the arbitration and had forced him to
appoint Abu Musa Ash'ari as their representative. He told them that he
found their present behavior very strange, considering their
involvement in Siffin. To this they admitted that they had sinned but
now they had repented for it and he should do the same.
Imam Ali (A.S.) replied that he was a true believer and did not haveto
repent because he hadnot committed any sin and dispersed them after
discussion.
The Kharjites refused to accept the words of Imam Ali (A.S.) and
awaited the decision of Amr al-Aas and Abu Musa Ash'ari. When they
learnt of the decision they decided to revolt, and they set up their
headquarters at Nahrawan, twelve miles from Baghdad. Some people came
from Basra to join the rebels.
On the other side, after hearing the verdict of Arbitration Imam Ali
(A.S.)rose for fighting the army of Syria and wrote to the Kharijites
that the verdict passed by the twoarbitrators in pursuance of their
heart's wishes instead of the Qur'an andsunnah was not acceptable to
him, that he had therefore decidedto fight with them and they should
support him for crushing the enemy. But the Kharijites gave him this
reply, "When you had agreed to Arbitration in our view you had turned
heretic. Now if you admit your heresy and offer repentance we will
think over this matter and decide what we should do." Imam Ali (A.S.)
understood from their reply that their disobedience and misguidance
had becomevery serious. To entertainany kind of hope from them now was
futile. Consequently, ignoring them he encamped in thevalley of
an-Nukhaylah with a view to marching towards Syria to fight against
Muawiya.
Imam Ali (A.S.) had already started towards Muawiya when he received
the news that they had butchered the governor of Nahrawan namely
Abdullah Ibn Khabbab Ibn al-Aratt and his slave maid with the child in
her womb, and have killed three women of Banu Tayyi and Umm Sinan
as-Saydawiyyah. Imam Ali (A.S.) sent al-Harith Ibn Murrah al-Abdi for
investigation but he too was killed by them. When their rebellion
reached this stage it was necessary to deal with them. There was a
danger that the Kharjites might attack Kufa while Imam Ali (A.S.)and
his men were marching towards Muawiya, so Imam Ali (A.S.) decided to
stop them. He changed his course eastward, crossed the river Tigris
and approached Nahrawan.
On reaching there Imam Ali (A.S.) sent a messengerto the Kharjites
demanding that those people who had murdered innocent Muslims around
their camp should be surrendered. The Kharjites replied that they were
all equally responsible for killing these sinners.
There was some reluctance in the army of Imam Ali (A.S.) to fight the
Kharjites, because they had been their companions against Muawiya at
Siffin. Imam Ali (A.S.) himself did not desire the bloodshed of these
misguided fanatics,so he sent Abu Ayyub al-Ansari with a message of
peace. So he spoke to them aloud, "Whoever comes under this banner or
separates from that party and goes to Kufah or al-Mada'in would get
amnesty and he would not be questioned. As a result of this Farwah Ibn
Nawfal al-Ashja'i said that he did not know why they were at war with
Imam Ali (A.S.). Saying this he separated along with five hundred men.
Similarly group after group began to separate and some of them joined
Imam Ali (A.S.). In the end, only cores of 1,800 die-hards were left
under the command of Abdallah binWahab. These Kharjites swore that
they would fight Imam Ali (A.S.) at any cost.
Nahjul Balagha - Sermon 36/Warning the people of Nahrawan of their fate:
"I am warning you that you will be killed on the bend of this canal
and onthe level of this low area while you will have no clear excuse
before Allah nor any open authority with you. You have come out of
your houses and then divine decree entangled you. I had advised you
against this arbitration but you rejected my advice like adversaries
and opponents till I turned my ideas in the direction of your wishes.
You are a group whose heads are devoid of wit and intelligence. May
you have no father! (Allah's woe be to you!) I have not put you in any
calamity nor wished you harm."
The Kharjites attacked Imam Ali's (A.S.) army with desperate courage.
However, they did not stand a chance against the superior army that
faced them and they were all killed except nine men. These nine
managed to flee to Basra and elsewhere, where they spread the fire of
their hatred and recruited more followers.From Imam Ali's (A.S.) army
only eight persons fell as martyrs. The battle took place on the 9th
Safar, 38 A.H. Two years later, in 40 A.H., it was theKharjites who
sent out three assassins to kill Imam Ali (A.S.), Muawiya and Amr
al-Aas. The lattertwo survived but Imam Ali (A.S.) was martyred
following Ibne Muljam's cowardly attack in the mosque of Kufa.
Having disposed of the Kharjites at Nahrawan, Imam Ali (A.S.) resumed
his march to Syria. However, the chiefs of hisfollowers urged him to
stop at Kufa to let the men rest before the long journey and to enable
the army to repair their weapons and armours. Imam Ali (A.S.) agreed
to this request and camped at Nukhayla outside Kufa.The soldiers were
allowed to leave the camp for a day.
On the next day, hardly any men returned and at length, Imam Ali
(A.S.) entered Kufa and gave a stern sermon to the people. However,
nobodycame forward and finally,Imam Ali (A.S.) turned away from them
in disappointment. The Syrian expedition was abandoned, never to be
resumed.