His men and Gordon sent him clothes that he had sent to them, and sent him a gift of Mahdist dervish attire. The two messengers came to Khartoum and entered before Gordon with their weapons, because he had sent them his weapons before entering. They stood before him, their hands on the hilts of his two swords. Gordon opened the reply and read it. The Mahdi was asking him to embrace Islam and threatening him with a long war and conquest, and that it would not be limited to Khartoum but would extend beyond it, as he was the awaited Mahdi. As for the prisoners, he said he would take care of their safety and keep them with him.

Gordon then realized that he had to fight the Mahdi, as there was no way to reconcile with him. So he began sending artillery to the Blue Nile every day, and the cannons fired at any enemies on the shore. The enemies, however, were approaching Khartoum day by day, demanding its rifles. From what Gordon wrote on the 20th of March, their number did not exceed fifteen hundred fighters, but he dared not go out for fear of the spread of the revolution's poison within Khartoum itself. At that time, news from outside had been cut off from Khartoum for three consecutive weeks, and the rest of the tribes and clans openly sided with the rebels, so Khartoum was under a complete siege. Gordon wrote a letter from there on March 21st, urging the British government to send reinforcements to break the Mahdi's power, saying he could withstand the siege of Khartoum for two months and requesting three thousand Turkish infantry and two thousand cavalry to settle the Sudan issue, defeat the Mahdi, and end the sedition he had stirred up.