After they were obliged to leave Makkah and immigrate to Madeenah, and after all the injustices and torture they went through, the Muslims were permitted to fight in order to defend themselves. Allaah, the Almighty, said (what means):

{Permission to fight is given to those (i.e. believers against disbelievers), who are fighting them, (and) because they (believers) have been wronged, and surely, Allaah is Able to give them (believers) victory Those who have been expelled from their homes unjustly only because they said: "Our Lord is Allaah.} [Quran 22:39-40]

The Prophet, sallallaahu alayhi wa sallam, himself commanded twenty-seven battles and he fought in nine of them: Badr, Uhud, Al-Khandaq, Banu Quraythah, Banu Al-Mustalaq,

Khaybar, the Conquest of Makkah , Hunayn, and At-Taa'if. The Prophet, sallallaahu alayhi wa sallam,

also gave the leadership of forty-seven military campaigns to his companions, may Allaah be pleased with them.

Under the leadership of the Prophet, sallallaahu alayhi wa sallam, the Muslims abided by the ethics of war. The teachings of the Prophet, sallallaahu alayhi wa sallam, were clear-cut that those who do not participate in wars should be kept away from all forms of harm. 

That is why he prohibited murdering children, women, and the elderly because Islam has come to build and reclaim the universe, not to destroy it.

The following are the most important battles in which the Prophet, sallallaahu alayhi wa sallam, fought:

The Great Battle of Badr

This battle took place on the 17^th of Ramadhaan in the second

Hijri year near the well of Badr which is between Makkah and

Madeenah.  The Messenger of Allaah, sallallaahu alayhi

 wa sallam,was informed that a caravan belonging

to the Quraysh,led by Abu Sufyaan Ibn Harb,

was on its way back from Levant to Makkah .

Thereupon, the Prophet, sallallaahu alayhi wa sallam, decided to capture this caravan so as to compensate the Muslims for

their property which the Quraysh tribe had confiscated in Makkah,

which was only fair. The Prophet, sallallaahu alayhi wa sallam,

 could not let the Quraysh tribe do business transactions safely,

  gain lots of money, and at the same time plot against

the Muslims.

It was necessary to pose a threat to the Quraysh business,

 as trade was its main source of income and power.

It was hoped that by feeling this threat, the Quraysh

tribe might reconsider its position and behavior and

enmity towards the Muslims.

When Abu Sufyaan was informed that the Prophet

 sallallaahu alayhi wa sallam, intended to capture the caravan,

so he sent a message to the Qurayshites in Makkah

  asking for help. Quraysh sent an army comprising

its best youths and horsemen that was commanded

by Abu Jahl.The caravan succeeded in escaping

from the Muslimswho reached the well of Badr.

Although the caravan was saved, Abu Jahl insisted on

fighting the Muslims and refused to return to Makkah,

 despite the factthat many of the Makkah leaders did not

want to fight. In response to the polytheists' determination to fight,

the Prophet, sallallaahu alayhi wa sallam, after consulting

his senior companions, may Allaah be pleased with them,

he had no other alternative but to go to war.

In this battle, the Muslims were only 314 men from

 the Immigrants (from Makkah) and the Supporters

(from Madeenah). On the other hand

the Quraysh army was about one thousand men

and it included their prominent figures and heroes.

 The battle started in the morning of the 17^th of Ramadhaan

 with skirmishes. Three polytheist heroes marched out

 calling for a duel. The Prophet,sallallaahu alayhi wa sallam,

asked his uncle, Hamzah Ibn 'Abdul-Muttalib and his cousins,

'Ali Ibn Abu Taalib, and `Ubaydah Ibn Al-Haarith to go

forward in combat. The Muslims managed to kill

the polytheist horsemen. Thereupon, the polytheists started

 their fierce attack against the Muslims who courageously

 defended and shielded themselves with faith and firmness.

 Then the Muslims started a counter-attack and

 the Prophet, sallallaahu alayhi wa sallam, entered

the battlefield. After fierce fighting, the polytheist army

was torn to pieces. Abu Jahl and many of the Quraysh

commanders were killed and their army was defeated.

The Muslims achieved a great victory and they obtained

large amounts of spoils of war.  Fourteen Muslims

were martyred in the battle while 70 polytheists were killed.

The Battle of Uhud

This battle took place near Mount Uhud to the north of Madeenah in Shawwaal of the third year after Hijrah.

The polytheists sought support from their allies and mobilized

an army made up of three thousand men to take revenge

for their destructive defeat in the Battle of Badr.

When the Prophet, sallallaahu alayhi wa sallam, knew that

the polytheists had moved to fight him, he mobilized an army to encounter them. He left Madeenah because the majority of

his companions, may Allaah be pleased with them, were of

the opinion that they should leave Madeenah and fight

the polytheists before reaching Madeenah.

The Prophet, sallallaahu alayhi wa sallam, was of

the opinion that they should remain in Madeenah and fight

the polytheists if they invaded.  However he,

sallallaahu alayhi wa sallam, approved of the opinion of

 the majority and marched to Mount Uhud. He kept

 the mountain behind him and faced the enemy.

The Messenger of Allaah, sallallaahu alayhi wa sallam,

 appointed fifty skillful archers to climb a high hill and protect

 the rear of the army, and ordered them not to leave

 their positions whether or not the Muslims were victorious. 

The fighting began and Allaah gave victory to the Muslims

over their enemy at the beginning. Believing that the battle

 was over, the Muslims became busy collecting the spoils of

war which the defeated polytheists had left behind.

On seeing this, the archers failed to follow

the Messenger’s, sallallaahu alayhi wa sallam,

instructions and they left their positions to take part in

the spoils collection like their fellow fighters.

On the other side, Khaalid Ibn Al-Waleed, who had not yet embraced Islam, noticed that the rear of the Muslim army was left unprotected by the archers. He, therefore, attacked the Muslim army who were taken by surprise. The Prophet, sallallaahu alayhi wa sallam, himself was wounded as a result and the Muslims were defeated, leaving seventy-one martyrs. The Muslims learned a most costly lesson when they failed to follow the instructions of the Prophet, sallallaahu alayhi wa sallam

The Battle of Khandaq (the Trench)

This battle took place in the fifth Hijri year. The polytheists of Quraysh, Banu Asad, and Ghatfaan allied together to fight

the Muslims. The army of the polytheists at this invasion

amounted to ten thousand men and they marched

 to Madeenah with the intention of eradicating the Muslims.

When the Muslims knew about their will to fight,

 they remained in Madeenah and started to dig a trench in

the North West area

 of Madeenah so as to thwart the advance of the allies.

The other directions of Madeenah were fortified by a large

number of palm dates and it was extremely difficult for

 the polytheists to penetrate through them.

The revered companion Salmaan Al-Faarisi, may Allaah

be pleased with him, was the one who advised the Muslims

 to dig the trench. The Prophet, sallallaahu alayhi wa

sallam,  himself participated in digging the trench although

he was fifty-seven years old at the time. When

the allied armies reached Madeenah,

they were surprised when they saw the trench

and were unable to cross it, because such techniques

 of war were not familiar to them.

The polytheists besieged Madeenah for a long time and

the Muslims suffered from much hardship.

The Jews of Banu Quraythah broke the agreement which

they had previously concluded with the Prophet.  

They agreed with the allies to join them when they were

 ready to attack Madeenah.

It happened that Nu'aym Ibn Mas'ood came to

the Messenger of Allaah, sallallaahu alayhi wa sallam,

and told him that he had embraced Islam.

Nu'aym used his wits in causing disunity among

the Quraysh, its allies,and the Banu Quraythah,

and managed to raise doubts among them.

Allaah sent a stormon a very cold winter night

that turned the polytheists’ cooking

 pots over and tore their tents apart.

 Abu Sufyaan, the commander of the allies,

 realized that it was no use staying there any longer,

 and he commanded the allies to leave. After they left,

the Prophet, sallallaahu alayhi wa sallam, said: "From now on,

 we will attack them (i.e. the disbelievers) but they cannot."

 [Al-Bukhaari]

This means that the Quraysh tribe would no longer be able to attack Madeenah.

The Battle of Banu Quraythah

The invasion of Banu Quraythah was due to failure to abide by the pact

they had made with the Messenger of Allaah, sallallaahu alayhi wa sallam,

when they supported the polytheist army against him in the battle of Al-Khandaq. 

The Muslim army marched out and besieged Banu Quraythah for more than twenty days until they accepted the Messenger’s judgment to assign an arbiter. He assigned Sa`d Ibn Mu'aath, may Allaah pleased with him, the chieftain of Al-Aws, who was a former ally of the Banu Quraythah. The arbiter ruled that the Banu Quraythah’s fighters should be killed in retaliation for their treachery and betrayal. When Sa`d issued this judgment, the Prophet, sallallaahu alayhi wa sallam, said to him: "Your judgment coincided with the judgment of Allaah."

Previously, the Muslims experienced the conspiracies and machinations of the Jews, so the Messenger of Allaah, sallallaahu alayhi wa sallam, expelled them from Madeenah. He did this with the Jews of Banu Qaynuqaa` after the Battle of Badr and the Jews of Banu An-Nadheer after the Battle of Uhud.

The Conquest of Makkah

The Quraysh tribe violated the treaty of Hudaybyyah they had made with the Prophet, sallallaahu alayhi wa sallam, They attacked the Khuzaa`ah tribe which was an ally of the Prophet, sallallaahu alayhi wa sallam. Thereupon the Prophet, sallallaahu alayhi wa sallam, decided to conquer Makkah. The Messenger of Allaah, sallallaahu alayhi wa sallam, commanding ten thousand fighters, marched to conquer Makkah at the beginning of the second week of Ramadhaan, 8 A.H.

When the Muslims approached Makkah, they pitched their tents and they made a glowing fire that lit up the whole valley. When Abu Sufyaan went   to check out the situation, he fell captive, and was brought to the Messenger of Allaah. Abu Sufyaan then embraced Islam. As a way of honoring him, the Prophet, sallallaahu alayhi wa sallam, "Whoever remains inside his house and locks his door is safe,   whoever enters the Sacred Mosque is safe, and whoever enters the house of Abu Sufyaan is safe."

The Messenger of Allaah, sallallaahu alayhi wa sallam, was keen to enter Makkah, the Holy Sanctuary, without fighting. He advised the commanders of his army not to fight except in case of emergency and within the limits.

The Prophet, sallallaahu alayhi wa sallam, entered Makkah victorious while he fled from it eight years ago after the Quraysh had conspired to kill him.

After he circumambulated the Ka`bah, the Prophet, sallallaahu alayhi wa sallam, gathered the people of Makkah , and said: "O you people of Quraysh! What do you think of the treatment that I am about to accord to you?"

They replied: "We expect nothing but good from you, O noble brother and son of a noble brother!"

After the conquest of Makkah, the Prophet, sallallaahu alayhi wa sallam, invaded Hawaazin and Thaqeef. He fought a fierce battle in which the Prophet, sallallaahu alayhi wa sallam, was steadfast after some of his companions, may Allaah be pleased with them, fled. The Prophet, sallallaahu alayhi wa sallam, remained steadfast in the battlefield, and said: "Where are you fleeing, O, people? Come back I am undoubtedly the Prophet!  I am the son of 'Abdul-Muttalib!"

Seeing the courage and the steadfastness of the Prophet, sallallaahu alayhi wa sallam, the fleeing companions, may Allaah be pleased with them, returned and managed to defeat Thaqeef and Hawaazin, and gained generous spoils of war.

The Battle of Tabook

This was the last battle fought by the Prophet, sallallaahu alayhi wa sallam, after Islam dominated the Arabian Peninsula. News reached the Prophet, sallallaahu alayhi wa sallam, that the Romans were preparing to attack the Muslims.  So, he mobilized a huge army of thirty thousand men. It was the largest army commanded by the Prophet, sallallaahu alayhi wa sallam.  It was called the Army of Distress because the distance to Tabook was very far, the weather was extremely hot, and the people were inclined to stay in their farms and gardens to harvest the fruit and enjoy the shade. Yet, the Muslim state was jeopardized and sacrificing was a must. The companions, may Allaah be pleased with them, sacrificed their entire wealth and participated in preparing and providing the army with weapons and equipment. `Uthmaan Ibn `Affaan, may Allaah be pleased with him, prepared one third of the army from his own money.

The Prophet, sallallaahu alayhi wa sallam, marched until he reached Tabook where he came to know that the Roman army, which was then the most powerful army in the world, fled to Levant out of fear. The Prophet, sallallaahu alayhi wa sallam, camped there for three weeks where he organized the affairs of this area and made some agreements with the small emirates there. After that, he returned to Madeenah to receive the delegations of the Arab tribes who came from every place in Arabia to declare their Islam and surrender to Allaah and His Messenger, sallallaahu alayhi wa sallam.