This is my favourite battle in all history. The Conquest of Khaybar was foretold in the Qur'an by Allah:
Commander of the Muslim Army - The Messenger of Allah (SAW)"Allâh has promised you abundant spoils that you will capture, and He has hastened for you this." [Quran 48:20]
Commander of the Jewish Army - Al Harith ben Abu Zaynab
Jewish pre-emptive attack
The Jews, going on the offensive, charged from Natat attacking the Muslim army's flanks. When the Muslims started their operations they met with much opposition, in particular from Jewish Khabarian archers, the best in Arabia, who wounded more than 50 Muslims. The Muslims pressed on with their attack for five days, but were met with no success. The Muslims did not make any gains on the sixth day, but on that night, a Jewish spy was caught, who was interrogated and told the Muslims that they should attack the fort of Naim.
The Jews, after a rather bloody skirmish in front of one of the fortresses, avoided combat in the open country. Most of the fighting consisted of shooting arrows at a great distance. On at least one occasion the Muslims were able to storm the fortresses. The besieged Jews managed to organize, under the cover of darkness, the transfer of people and treasures from one fortress to another as needed to make their resistance more effective. Neither the Jews nor the Muslims were prepared for an extended siege, and both suffered from a lack of provisions. The Jews, initially overconfident in their strength, failed to prepare even enough water supplies for a short siege.
THEN THE HIGHLIGHT OF THE BATTLE - THE BANNER IS GIVEN TO ALI (RA)
Sahih Bukhari, Volume 5, Book 59, Hadith Number 521:
"Narrated Sahl bin Sad: On the day of Khaibar, Allah's Apostle said, "Tomorrow I will give this flag to a man through whose hands Allah will give us victory. He loves Allah and His Apostle, and he is loved by Allah and His Apostle." The people remained that night, wondering as to who would be given it. In the morning the people went to Allah's Apostle and everyone of them was hopeful to receive it (i.e. the flag). The Prophet said, "Where is Ali bin Abi Talib?" It was said, "He is suffering from eye trouble O Allah's Apostle." He said, "Send for him." 'Ali was brought and Allah's Apostle spat in his eye and invoked good upon him. So 'Ali was cured as if he never had any trouble. Then the Prophet gave him the flag. 'Ali said "O Allah's Apostle! I will fight with them till they become like us." Allah's Apostle said, "Proceed and do not hurry. When you enter their territory, call them to embrace Islam and inform them of Allah's Rights which they should observe, for by Allah, even if a single man is led on the right path (of Islam) by Allah through you, then that will be better for you than the nice red camels. "
ALLAHU AKBAR