The conquest of Makkah established Ka'bah, the House of God built by Prophet Abraham (PBUH) thousands of years ago, as the spiritual centre of Islam.
The 10-year Hudaibiyah treaty, signed in 6 AH, had brought peace to Arabia and gave freedom to the tribes to side with the Quraish of Makkah or the Muslims of Medinah.
The Banu Khuza'ah sided with the Muslims and the Banu Bakr allied themselves with the Quraish. Two years later, without provocation, the Banu Bakr attacked the sleeping Banu Khuza'ah. The Banu khuza'ah took refuge in Al Ka'bah but were butchered in the sacred precincts.
Hearing of this violation Prophet Mohammad (PBUH) said, "I will prevent from you what I will prevent from myself." He sent an ultimatum to Quraish to compensate the victims, to withdraw their support of the Banu Bakr or to declare the Hudaibiyah pact invalid. The Quraish cancelled the truce and the Prophet (PBUH) decided to take action.
On Wednesday 10 Ramadan, 8 AH, he set off towards Makkah with an army of 10,000. As fulfilled by Moses prophecy in Deuteronomy 33:2 "he came with ten thousands of Holy Ones". Many of the men kept the fast, even though they were not obliged to because they were travelling.
The Prophet (PBUH) camped at Marr uz Zahran, lighting huge fires in every camp to make his army appear even larger. Al Abbas, the Prophet's (PBUH) uncle, encountered the camp 25 kilometers out on his emigration as a messenger of peace.
The Quraish had no power to resist the mighty advance. Abu Sufyan, the Quraish leader, saw there was no escape. He went with Al Abbas to the Prophet (PBUH), who granted him an unconditional pardon and declared his home a safe house.
As the Muslims approached Makkah, Ikrimah Bin Abu Jahl attacked his old friend Khalid Ibn Walid's section of the Muslim army, killing two Muslims, but losing a dozen Quraish. Apart from this skirmish there was no resistance.
The Prophet (PBUH) recited "Verily we have granted thee manifest victory"
Al-Quran, Sura Al Fath (The Victory) 48:1
The Muslim army entered Makkah on the 20th of Ramadan. When the Prophet (PBUH) arrived he descended his camel and then rode on to encircle the Ka'bah (tawaf). He recited "O mankind! Lo! We have created you male and female, and we have made you nations and tribes so you may know each other."
The prophet (PBUH) turned to Ka'bah. Pointing his staff at 365 idols placed there he recited: "Truth prevails, falsehood vanishes" Sura Al-Isra, 17:81
The idols fell on their faces.
The Prophet (PBUH) ordered Bilal to climb on top of Ka'bah and perform the call to prayer, which has been heard five times a day there since. Uthman bin Talha was made custodian of the key of Ka'bah.
The Prophet (PBUH) addressed the people saying "I wiil treat you asa Joseph treated his brothers" (Ibn Hisham, Tibari, Ibn Qiyyam). "This day let no reproach be cast on you: God will forgive you and He is the most merciful of those who show mercy". Sura Yusuf, 12:92
He declared a general amnesty for the entire community, despite the 13 years of cruelty to the Muslims before the emigration to Medinah. Those responsible for the death of his wife, Khadijah, his uncle Abu Talib, his daughter Zainab and Abu Sufyan's wife, Hind, who had cut open his uncle Hamza and eaten his liver, were forgiven.
On the second day of the campaign the Prophet (PBUH) said "God made Makkah holy the day He created heaven and earth and it is the holy of the holiest until the Resurrection Day. It is not lawful for anyone who believes in God and the last day to shed blood therein, nor to cut down trees therein.
The sale of liquor and usury were forbidden at this point.
The Prophet (PBUH) remained in Makkah 29 days until Shawwal 9, 8 AH., the people of Makkah entering the fold of Islam in droves.