The 2 years following this event proved the truth of these words. Such leading Qurayshi figures as Khalid ibn Walid and 'Amr ibn al-'As became Muslims, and Islam spread across Arabia. Jewish conspiracies were ended, and Islam crossed into other lands through the letters sent to neighboring kings. At the end of this period, the Banu Bakr (a Qurayshi ally) attacked the Banu Khuda'a (the Muslims' ally) and killed some of them. The truce between the Muslims and the Quraysh was now over. No longer able to resist the Muslims, Abu Sufyan came to Madina in the hopes of renewing it. However, the Messenger refused to meet with him. 
The Messenger began to prepare for war. As always, he kept the affair quite secret and no one, including his wives and closest friends, knew where the campaign would be. When Abu Bakr asked his daughter 'A'isha, the wife of the Messenger, where the Messenger intended to march, she told him that she did not know.  However, an Emigrant named Khatib ibn Abi Balta'a guessed his intention and sent a letter to the Quraysh informing them of the Messenger's preparations. The Messenger, learning of this through Revelation, ordered 'Ali and Zubayr to take the letter from the woman to whom Khatib had entrusted it. They did this successfully. 
The Messenger left Madina with 10,000 men. Two years before, they had numbered 1,600 when his attempted minor pilgrimage ('umra) resulted in the treaty of Hudaybiya. The resulting peaceful atmosphere caused many to reconsider and accept Islam.
The Companions did not know the destination until they were ordered to head for Makka. When they approached this holy city, the Messenger ordered each soldier to light a fire, for the Makkans would light a fire for every tent while traveling in the desert.  As a result, they estimated the Muslim army to consist of about 30,000 men. Having no realistic way to resist, they surrendered. Abu Sufyan, who had been invited by the Messenger to see the Muslim army, also advised this.
The Messenger did not desire bloodshed. Dividing his army into six columns, each one entered Makka through a different route. He ordered the commanders to avoid bloodshed unless they were attacked. To realize this goal and conquer Makka peacefully, he announced: "Those who shelter in the Ka'ba are safe, those who shelter in Abu Sufyan's house are safe, and those who stay in their own houses are safe." 
Being a Prophet of absolute mercy, one who came to secure the happiness of humanity both in this world and the next, the Messenger entered Makka, bowing on the back of his mule, as a victorious conqueror. He displayed no self-pride and had no thought of vengeance or retaliation. He proceeded toward the Ka'ba in complete modesty and absolute gratitude to God, who had made him victorious in his sacred mission. Stopping at the Ka'ba, he asked his enemies: "How do you expect me to treat you?" They replied: "You are a noble man, the son of a noble man." The Messenger stated: "This day there will be no reproach on you. God will forgive you; He is the Most Merciful of the Merciful. You can go away." 
This marked the end of polytheism in Makka. While he was destroying the idols at the Ka'ba, he recited: "Say: 'Truth has come and falsehood has disappeared. Indeed falsehood is subject to disappearance.'" (17:81)  Almost all Makkans now became Companions, although just one day before they had been his enemies.
 Ibn Hisham, 4:39.
 Ibn Hisham, 4:41.
 Ibn Kathir, al-Bidaya, 4:330; Ibn Hisham, 6:41–5.
 Ibn Kathir, ibid., 4:331–2.
 Ibn Sa'd, 2:142; Ibn Hisham, 4:55; Tabari, 3:120; Balazuri, Futuh al-Buldan, 1:47.
 Bukhari, 5:93; Muslim, 3:1408; Ibn Hisham, 4:59; Ibn Sa'd, 2:136.