This is an extract from the book "The Islamic State" by Sheikh Taqiuddin an-Nabahani.
In the second year of the Hijrah, the Messenger of Allah صلى الله عليه وآله وسلم set out on the 8th of Ramadhan with three hundred and five of his Sahabah mounted on seventy camels. ‘Amr ibn Umm Maktum was assigned to lead the prayer while Abu Lubabah was left in charge of Madinah.
They rode the camels in turn heading towards a caravan led by Abu Sufyan. As they marched on, they sought news of the caravan until they had reached the valley of Dafran where they settled, and news reached them there that the Quraysh had set out from Makkah to protect their caravan. The whole affair then assumed different proportions for it was no longer the caravan, the question was whether to confront the Quraysh or not. So Allah's Messenger صلى الله عليه وآله وسلم consulted the Muslims. Abu Bakr and then ‘Umar voiced their opinions, then al-Miqdad ibn ‘Amr arose and said,
"O Messenger of Allah! Go where Allah tells you, for we are with you. We shall not say as the children of Israel said to Moses ‘You and your Lord go and fight and we will stay at home', but you and your Lord go and fight and we will fight with you."
The Muslims then went silent, and he صلى الله عليه وآله وسلم said, "Give me advice O men!" by which he meant the Ansar who had paid allegiance to him at al-‘Aqabah. They had pledged to protect him as they protected their wives and children, with the stipulation that they were not responsible to fight with him outside Madinah. When the Ansar sensed that he صلى الله عليه وآله وسلم meant them, Sa'd ibn Mu'adh who was holding their banner said, "It seems as if you mean us, O Messenger of Allah." He صلى الله عليه وآله وسلم said, "Yes." Sa'd said, "We believe in you, we declare your truth, and we witness that what you have brought us is the truth, and we have given you our word and agreement to hear and obey; so go where you wish, we are with you; and by He who sent you, if you were to ask us to cross this sea and you plunged into it, we would plunge into it with you; not a man would stay behind. We do not dislike the idea of meeting our enemy tomorrow. We are experienced in war, capable of fighting. It may well be that Allah will let us show you something which will bring you joy, so take us along with Allah's blessing." The Messenger of Allah صلى الله عليه وآله وسلم was delighted with Sa'd's words and said, "Proceed with full confidence, for Allah has promised me one of the two parties, and by Allah, it is as though I can now see the place where they will be killed."
The Messenger of Allah صلى الله عليه وآله وسلم and his Sahabah journeyed until they had nearly reached Badr. They realized that the Quraysh's troops were nearby and so ‘Ali, al-Zubayr ibn ‘Awwam, and Sa'd ibn Abi Waqqas with a number of his Sahabah were sent to the well at Badr in search of news. They returned with two young men whom they questioned. They disclosed the number of the Quraysh at between nine hundred to a thousand men and that the nobles of the Quraysh were out in force to protect the caravan. The Messenger of Allah صلى الله عليه وآله وسلم realized that they were facing a force which was three times the size of his own and that he would be in for a fierce battle. He صلى الله عليه وآله وسلم informed the Muslims that Makkah had thrown out the pieces of its liver (or the best of her sons) into the battle and that they should harden their resolve.
The Muslims vowed to stand up to the enemy, they settled by the well of Badr where they built a cistern and filled it with water. Then they stopped up all the other wells so that they would have plenty of water and the enemy would have nothing to drink, at the same time they also built a canopy for the Messenger of Allah صلى الله عليه وآله وسلم to reside in. The Quraysh took up their positions and the skirmishes of battle began. Al-Aswad ibn ‘Abd al-Asad stepped forward to destroy the cistern that the Muslims had built. Hamzah dealt with him by smiting him and sending his foot flying. He fell on his back with blood streaming from his foot and Hamzah followed him and struck him, killing him near the cistern. Then, ‘Utbah ibn Rabi'ah stepped forth between his brother Shayba and his son al-Walid. Hamzah, ‘Ali and ‘Ubaydah ibn al-Harith stepped forward to meet them. Hamzah quickly dealt Shayba a blow and ‘Ali soon disposed of al-Walid. Hamzah and ‘Ali turned on ‘Utbah who stood firm against ‘Ubaydah and they dispatched him, carrying off their injured companion afterwards.
Then the two sides advanced and drew near each other on Friday morning on the 17th of Ramadhan. The Messenger of Allah صلى الله عليه وآله وسلم straightened the ranks and incited the Muslims to fight. The Muslims were encouraged by Allah's Messenger's words and went forward. The fighting broke out fiercely and Qurayshi heads went flying from their bodies, the Muslims becoming stronger in belief all the time chanting ‘Ahad! Ahad!' (the One! the One!). Allah's Messenger صلى الله عليه وآله وسلم stood in the middle of the melee, took a handful of pebbles and threw them at the Quraysh saying, "Foul be those faces!" Then he صلى الله عليه وآله وسلم ordered his Sahabah to charge and they duly obliged until the battle was over and the foe was routed. The Muslims emerged victorious, slaying many warriors and tribal leaders of the Quraysh and capturing many more. The Quraysh fled the battlefield and the Muslims returned to Madinah having achieved a truly great victory.