The Brute Ibn Ziyad at Kufa got the information of Imam Hussain's getting out of the control of Hurr and also learnt that Imam Hussain (pbuh) had camped near the river Euphrates known as the Al-Qama.
On the 3rd of Muharram Ubayd Allah son of Ziyad sent an army counting four thousand led by Umar son of Saad Abi Waqqas were the first to move towards Karbala. His orders were to get Imam Hussain (pbuh) to surrender to Yazid. When Imam Hussain (pbuh) refused, Umar son of Saad told Ubayd Allah son of Ziyad to send more troops. Ubayd Allah son of Ziyad ordered all the men in Kufa to come out and join the army to fight against Hussain. Anyone not doing so would be killed. Whoever brings the head of Hussain will get a great prize and I will make him the Governor of Al-Ray province.
Regiment after regiment began to pour in on the plain of Karbala from all sides until they were thirty thousand (30,000) and ultimately the enemy's forces compelled Imam Hussain (pbuh) to shift his camp from the bank of the river to the interior of the burning desert. Hussain's brother, the lion-hearted Abbas (pbuh), objected to this demand from the enemy, claiming priority of occupation and the right of the son of the Holy Prophet, the Holy Imam (pbuh), to stay where he had first camped. When the enemy wished to march towards the Holy Imam's camp, the brave Abbas at once drew his sword and stood firm and shouted to the men: "If you advance one step forward, you shall lay headless there."
Knowing the bravery, valor, and prowess of the valiant son of Ali, the Lion of God, none cared to step forward. But Imam Hussain (pbuh) called his Brother saying:
Do you not see that truth is not being practiced and wrong not being discouraged? The righteous believer is the one who aspirers towards righteousness. I alone consider death to be a prosperity, while living with the oppressors is nothing but undesirable. Imam Hussain (p.b.u.h.)
"Brother Abbas! Let not bloodshed be initiated from our side. Let them occupy any place they like. They call themselves my Grandfather's followers. Let them enjoy every comfort they want. We shall suffer for them, being away from the water. When God is with us, Brother, what if, the river is far away from us."
With these words, Imam Hussain (pbuh), in order to avoid bloodshed, issued orders to shift this camp several miles into the interior of the burning desert and it was immediately done. Also Imam Hussain (pbuh) did not want the people to think that the battle in Karbala was about water.
No room for any criticism left:
If the Holy Imam (pbuh) had stayed at Madina and got slain there, it would have been said, why did he not migrate to Makkah to take shelter in the Great Sanctuary there? He did go to the Kaaba and if he had stayed there to be killed by Yazid's agents, it would have been said why did he not leave the holy place to avoid bloodshed in the Great Sanctuary? Imam Hussain (pbuh) left Makkah too, even though it was the very eve of the pilgrimage. And if he had gone to Kufa it would have been said why he went to a place where his Deputy Muslim had been killed, and when he knew the situation there. Imam Hussain (pbuh) avoided going to Kufa. Imam Hussain (pbuh) also availed of the opportunity given by Hurr. Now when the enemy became cruel, heartless and aggressive, he avoided bloodshed by shifting his camp into the interior of the desert, abandoning the bank of the river to the enemy.
Imam Hussain (pbuh) besieged at Karbala:
When the whole plain of Karbala was full with Yazid's regiments and the Imam Hussain's camp was totally surrounded by the enemy's forces, Son of Saad the Commander of the Brute armies met Imam Hussain (pbuh) on the banks of the river and demanded 'allegiance' on behalf of the tyrant Yazid and said:
"If you pay homage to Yazid, everything will go well for you and whatever worldly comforts and privileges you desire for, will be at your disposal. Otherwise, it will end in a wholesale massacre of yourself and all your dear ones here."
Imam Hussain (pbuh) firmly refused to pay the 'allegiance' saying:
"Tell Yazid to tempt with the worldly comforts to those who are after this World. I am the Imam, the representative of the Apostle of God. I shall never yield to the one who believe not in God and who defied the Word of the Lord, in word and deed, and who spread godlessness on the earth. Let any calamity befall on me and my dear ones, the will of the Lord shall be followed. Hussain will cheerfully meet any catastrophe but never surrender Truth to falsehood."
Water supply to Imam Hussain's camp cut off:
At last on the 7th Muharram 61 Hijra the Commander of Yazid's forces received orders to cut off all sources of supply to the Holy Imam's camp and not allow even a drop of water to reach any of the inmates therein. It can better be imagined than described what the condition of Imam Hussain's camp would have been under the scorching Arabian sun. The camp was in the midst of the burning desert, with the heat-waves blowing from all sides. The unavailability of water, with nothing to feed even the young children, the wriggling of the babies for milk which the poor mothers, who were themselves suffering from the killing thirst, could not give, caused distress. What a torturous situation it must be, and how did those Holy ones suffer all these unbearable tortures, it is very difficult for any human mind to conceive, but all these are facts which the Holy Imam (pbuh) and his Godly companions suffered with wonderful fortitude and patience. Over and above all these tortures, the sight of the enemy's forces preparing all around for the massacre and a wholesale destruction was there, before the ladies and the children in the besieged camp. Hurr remembered how kind Imam Hussain (pbuh) was when he needed water. He asked Umar son of Saad to give water to Imam Hussain's camp or at least to the children, but Umar son of Saad showed no pity.
Note: Abbas the Standard Bearer, had already come to receive the nickname 'Saqqa' (water carrier), as earlier, on one or two occasions, at nights he had been able to pass through the enemy's ranks to fetch water for the children. It was not the case that they had not drunk any water for three days and nights. Access to water had been closed for three days and nights, but during this time they had been able to get some water on one or two occasions, including the night of 'Ashura', when they had taken bath and washed their bodies.
Enemy decides to attack:
All efforts of the enemy through temptations, promises, persecutions and tortures, to persuade the Holy Imam, to yield to Yazid were in vain. Even the killing heat of the desert and the thirst of three continuous days suffered by himself, his faithful companions, the helpless ladies and even the innocent infants and the babies, could not move the Holy Imam (pbuh) to effect the least change in the strength of his will re-establish the Truth paying any price the task might demand. On the 9th of Muharram a final warning was sent to Imam Hussain (pbuh) from Umar son of Saad that if he did not surrender, he would be killed. Imam Hussain (pbuh) refused to bow down to his threats. The enemy's forces advanced towards the camp of the Holy Imam (pbuh) to affect a wholesale massacre of all the inmates therein. Imam Hussain (pbuh) sent word to the enemy's Commander, Umar son of Saad through the brave Abbas (pbuh) with the request for a night's time to spend it in his last prayers to the Lord which was at first refused but ultimately with much reluctance granted.