First I want to begin with the Reasons of the Battle of Badr:
Meccan polytheists were not happy about the Muslims’ migration to Medina. They were still angry at Muslims who left their homeland. Moreover, Meccans took all the properties of the Muslims that were left in Mecca, and loaded them in a trade caravan that was going to Damascus. This way, they would get money by selling the properties of Muslims. When Muslims heard of this, they wanted to prevent the caravan, because they knew that the caravan was going to stop near Medina on its route. The plan was that when Muslims saw the caravan, they would take all their possessions back from Meccans.
Abu Sufyan, who was the leader of the caravan, heard of this plan and sent a word to Meccan leaders to ask for their help. When Abu Jahl heard this, he immediately prepared for a war because this was a great opportunity for him to show Meccan power to everyone, especially to Muslims.
However, not everyone in Mecca was willing to fight. There were some Meccans who had brothers, sons, or fathers on the Muslim side, so obviously they didn’t want to fight with their family members. However, Abu Jahl forced everybody to join this war, so they had to participate in it unwillingly.
On the other hand, Abu Sufyan had changed the route of the caravan without stopping in Medina. He told the leaders of Mecca that there was no need to fight because he was able to return the caravan back to Mecca safely and nobody or nothing in the caravan would be harmed. However, Abu Jahl was already prepared for fighting. He said:
“We are not going to return, without destroying Muhammad and his friends”.
Meanwhile, the Prophet got news of the Meccan’s preparations for war. The Muslims did not really want to fight with Meccans. However, they were coming towards Medina to destroy them, and also Allah sent a revelation giving Muslims permission to fight back and defend themselves. The verse says:
“Permission to fight has been given to those who are being fought, because they were wronged. And indeed, Allah has full power to help them to victory.” (22:39)
After this Qur’anic revelation, Muslims went to the field of Badr, and waited for the Meccans to come. That whole night, Allah’s messenger prayed to God to grant them victory, because the number of Muslims were very few as opposed to the Meccans. The Meccan army had 950 soldiers whereas Muslims had only 313 soldiers. After the prayer, Allah sent Muslims the good news that He would sent thousands of angels to help them in the battle.
The next day, both sides were ready to fight; but, before the fight started, the Messenger of Allah sent Omar to the other side as an envoy to propose peace, saying that there is no need to fight, they could go back if they want. But Abu Jahl, the leader of the Meccans, certainly did not accept their suggestion. He was so full of hatred that he responded:
“We will show everyone our power and fame with this battle!”
So the battle began. Allah sent the three archangels—Jabrail, Michael, and Israfil—and a thousand angels for each of them. So the angels fought in the Muslim side. The battle took 3 hours. Before the battle started, God’s messenger had told his companions not to touch some of the Meccans unless they attacked first, because, there were some groups in the Meccan army who didn’t want to fight with Muslims but had been forced to join the army because of the pressure of Abu Jahl, as we said before.
As a result of the battle, the Meccan army fled and the Muslims won through Allah’s help. 14 Muslims and 70 non-Muslims died in the battle. Many important Meccans died, including Abu Jahl; and 70 of them were taken as captives.
What happened to the captives?.. After staying for a few days with Muslim families, the Messenger of Allah freed some of the captives in exchange for ransom; and freed others for teaching ten Muslims to read and write; and some others for promising not to speak badly of Islam or help against Muslims.
So all of the captives returned to Mecca except for a few of them who preferred to be Muslim and stay with Muslim families.
So this was the summary of the reasons and the results of the Battle of Badr.