zam said:
muslim history remembered him as " sword of God", which killed lots of muslims during the Uhad battle and was one of the cause of Prophet Mohammad's saww teeth.......remembrance day.
Battle of Mu'tah and Sword of Allah (629)
Main article: Battle of Mu'tah
Three months after Khalid's arrival to Medina, Muhammad sent an envoy to the Ghassanids with a letter asking the chieftain to accept Islam. While passing through Mu'tah, this envoy was intercepted and killed by a local Ghassanid chieftain by the name of Shurahbil ibn Amr. Traditionally, diplomatic envoys held immunity from attack, and the news of this act enraged Medina.[citation needed]
An expedition was immediately prepared to take punitive action against the Ghassanids. Muhammad appointed Zayd ibn Harithah as the commander of the force. In the event of Zayd's death, the command was to be taken over by Ja`far ibn Abī Tālib, and if Jafar were to be killed, the command would be in the hands of `Abd Allah ibn Rawahah. In the event that all three were killed, the men of the expedition were to select a commander from amongst themselves.[4]
During the battle, the three named commanders were slain, and Khalid was selected as the commander. He was able to maintain his army of 3,000 soldiers against a massive army of the Byzantine Empire and Ghassanid Arabs in what would be known as the Battle of Mu'tah. The size of the combined forces of Ghassanid and Byzantines is recorded in early sources at an estimated 200,000. Khalid assumed command of the Muslim army at the crucial moment, and turned what would have been a defeat into a strategic retreat. During nightfall, Khalid ordered the men of the right flank to change places with those of the left, and the men of the front lines with those of the rear guard. He also sent a group of men behind the main army and they were commanded to make a large commotion. At first light, when the enemy armies assembled to face the Muslim front lines they saw new and unfamiliar faces, coupled with a cloud of smoke behind the Muslim lines. The obvious conclusion to this was that the Muslims had received reinforcements. As the Muslim army retreated. Khalid was the last one to leave the battle and he broke 9 swords covering the Muslim's backs. Believing a trap was waiting for them, the Byzantine troops did not pursue. After the Battle of Mu'tah, Khalid was given the title Sword of Allah for bringing back his army to fight another day.[5]
In 630 AD, the Muslims advanced from Medina to conquer Mecca. In the Conquest of Mecca Khalid commanded one of the four Muslims armies that entered Mecca from four different routes, and he had a skirmish with the Qurayshi cavalry. Later that year, he participated in the Battle of Hunayn and the Siege of Ta'if. He was also sent to the Banu Jadhimah tribe. He was part of the Tabuk campaign under the command of Muhammad, and from there he was sent to Daumat-ul-Jandal where he fought and captured the Arab Prince of Daumat-ul-Jandal, thus forcing Daumat-ul-Jandal to submit.
In 631 A.D he participated in the farewell hajj of Muhammad. During the Battle of al-Yarmuk, Khalid ibn al-Walid lost a helmet (qalansuwah) he always wore to battle. He asked the people to help him find it and they searched repeatedly until it was found. They saw it was a very old qalansuwah and thought it strange that Khalid ibn al*-Walid was so insistent on finding it. Khalid ibn al*-Walid told them: "The Prophet performed Umrah and then shaved his head. I rushed with the people to get some of his hair. I got some of the hair from the front part of his head which I put in this qalansuwah. Every time I went into battle with this qalanwuwah, Allah gave me victory."