The first 18 months at Medina were spent in settling down.

Muhammad was given a piece of land and had a house built, which eventually held apartments grouped around a central courtyard for each of his wives.

The Muslims often joined Muhammad at prayers in his home, which, after his death, became the mosque of Medina.

The emigrants (muhajirun, the men from Mecca) were at first guests of brother Muslims in Medina, but Muhammad did not contemplate this situation continuing indefinitely.

A few emigrants carried on trade in the local market run by a Jewish clan.

Others, with the approval of Muhammad, set out in normal Arab fashion on razzias (ghazawat, "raids") in the hope of intercepting Meccan caravans passing near Medina on their way to Syria.

Muhammad himself led three such razzias in 623 CE.

They all failed, probably because traitors betrayed the Muslim movements to the enemy.

At last, in January 624 CE, a small band of men was sent eastward with sealed orders telling them to proceed to Nakhlah, near Mecca, and attack a caravan from Yemen.

This they did successfully, and in doing so they violated pagan ideas of sanctity--thereby making the Meccans aware of the seriousness of the threat from Muhammad.

About the same time there was a change in Muhammad's general policy in important respects. One aspect was the "break with Jews"; instead of making concessions to the Jews in the hope of gaining recognition of his being the prophet of God, he asserted the specifically Arabian character of the Islamic religion.

Hitherto the Muslims had faced Jerusalem in prayer, but a revelation now bade them face Mecca. It is possible that because of this change that Muslims of Medina were more willing to support Muhammad.

In March 624 CE he was able to lead about 315 men on a razzia to attack a wealthy Meccan caravan returning from Syria.

The caravan, led by Abu Sufyan, the head of the Umayyah clan, eluded the Muslims by devious routes and forced marches.

Abu Jahl, the head of the Makhzum clan, however, leading a supporting force of perhaps 800 men, wanted to teach Muhammad a lesson encountered Muhammad’s 315 men.

On March 15, 624 CE, near a place called Badr, the two forces found themselves in a situation, perhaps contrived by Muhammad, from which neither could withdraw without disgrace.

In the ensuing battle at least 45 Meccans were killed, including Abu Jahl and other leading men, and nearly 70 taken prisoner, while only 14 Muslims died.

To Muhammad this appeared to be a divine vindication of his being the prophet of God, and he and all the Muslims were greatly elated by this significant victory.

In the flush of victory some persons in Medina who had satirized Muhammad in verse were assassinated, perhaps with his connivance.

He also made a minor disturbance an excuse for expelling the Jewish clan which ran the local market.

This weakened Muhammad’s most serious opponent in Medina, the "hypocrite" (munafiq), or nominal Muslim, 'Abd Allah ibn Ubayy, who was allied with the local Jews.

The remaining “waverers” among the Arabs probably became serious Muslims about this time.

Thus the victory of Badr greatly strengthened Muhammad and his position of leadership.

At the same time he was using marriage relationships to bring greater cohesion to the emigrants. Of his daughters, Fatimah was married to 'Ali (later fourth caliph, or leader of the Islamic community) and Umm Kulthum to 'Uthman (third caliph).

He himself was already married to 'A'ishah, daughter of Abu Bakr (first caliph), and was now espoused also to Hafsah, daughter of 'Umar (second caliph), whose previous husband was one of the Muslims killed at Badr.

In the same year Muhammad led larger Muslim forces on razzias against hostile nomadic tribes and had some success.

Obviously, he realized that the Meccans were bound to try to avenge their defeat.

Indeed, Abu Sufyan was energetically mobilizing Meccan power to defeat Muhammad.

On March 21, 625 CE, Abu Sufyan entered the oasis of Medina with 3,000 men.

One of the striking features of Medina was a large number of small forts that were impregnable to Arab weapons and tactics.

Muhammad would have preferred the Muslims to retire to these; but those whose cereal crops were being laid waste by Abu Sufyan and his 3000 persuaded him to go out to fight.

By a night march with 1,000 men, he reached the hill of Uhud on the further side of the Meccan camp.

On the morning of March 23 the Meccan infantry under Abu Sufyan attacked and was repulsed with considerable loss.

As the Medina Muslims pursued, the Meccan cavalry launched a flank attack after the archers guarding the Muslim positions had abandoned their position.

The Medina Muslims were thrown into confusion.

Some made for a fort and were cut down, but Muhammad and the bulk of his force managed to gain the lower slopes of Uhud, where they were safe from the cavalry.

The Meccans, because of their losses, were unable to press home their advantages and without delay set out for home, while Muhammad the next day made a show of pursuing them.

The battle at Medina produced neither a clear victor nor loser.

In Badr and Uhud together, the Meccans had killed about as many men as they had lost; but they had boasted that they would make the Medina Muslims pay several times over, and they had not shown the degree of superiority appropriate to their leadership claims in Arabia.

Muhammad, though he had lost above 70 men, realized that this was a military reverse, not a defeat; but the confidence of the Medina Muslims and perhaps his own had been struck a serious blow.

If the victory of Badr was a sign of God's support, did Uhud indicate that he had abandoned the Muslims?

Muhammad's faith soon overcame any momentary doubts, and he was gradually able to restore the confidence of his followers.

For two years after Uhud, both sides prepared for a decisive encounter.

In the razzias Muhammad led or sanctioned, he seems to have aimed at extending his own alliances and at preventing others from joining the Meccans.

In at least two cases a small party of Muslims was tricked or ambushed, and most of their lives were lost.

As a result, another Jewish clan was expelled from Medina.

At length, in April 627 Abu Sufyan led a great confederacy of 10,000 men against Medina.

On this occasion Muhammad had ordered the crops to be harvested and a trench to be dug to defend the main part of the oasis from the Meccan cavalry.

This became known as the “battle of the trench”, or the “battle of the ditch”.

For a fortnight the Meccan confederates besieged the Medina Muslims.

Attempts to cross the trench failed, and fodder for the horses was scarce, while Muhammad's agents among the attackers fomented potential dissensions.

Then, after a night of wind and rain the great army melted away.

The Meccans had exerted their utmost might and had failed to dislodge Muhammad, whose position was now greatly strengthened.

For more than two years now there had been opposition to Muhammad in Medina, chiefly from 'Abd Allah ibn Ubayy and other so-called “hypocrites” (munafiquin) who had abandoned Muhammad at Uhud and who together had fostered disaffection.

Shortly before the siege Muhammad had a showdown with 'Abd Allah ibn Ubayy, who had joined in spreading slanders about Muhammad's wife 'A'ishah.

This confrontation revealed that 'Abd Allah had little support in Medina.  He was then reconciled to Muhammad.

After the siege of Medina, Muhammad attacked the Jewish clan of Qurayzah, which had probably been instigating intrigue against Muhammad.