Khalid ibn al-Walid was a born fighter and also turned out to be a great military leader. He was a Meccan from the Quraysh tribe from which Prophet (pbuh) also came. The Quraysh was the tribe that controlled Mecca and the Ka’aba, the first house of prayer constructed at the decree of Allah (God) Al-Mighty, by Ibraham (AS).
Khalid ibn-alwaliid left to the mountains during the compulsary ummrah of treaty of hudaibiyah and came back when the muslims were finished only to find a letter written to him by his muslim brother(al-waliid ibn al-waliid) the letter convinced khalid to become a muslim and he set out to go to madinah and accepted islam there
Ashadu anla ilaha ila allah, ash hadu ana muhammad rasulallah
The first battle khalid Ibn Al-walid won was the fight with Byzantine army the war was called the battle of Mu’tah was on the northern borders of arabian peninsula the army of Byzantine had 25,000 soldiers and the muslims had 30,000 men the fight was outside of tabuk it began in march 634
The battle of Mu’tah had he odds favoured against the Muslims and when it looked like the Muslims were going to lose, Khalid Ibn Al-Walid came up with a genius plan to ensure the muslims retreat