The Rashidun Caliphate expanded rapidly; within the span of 24 years, a vast territory was conquered comprising
Mesopotamia, the
Levant, parts of
Anatolia, and most of the
Sasanian Empire. Some explanations for the success of the Arab invasion of the empires to the north, west and east initiated by the Rashidun were the weakening of the two empires brought on by wars between them (especially the
Byzantine–Sasanian War of 602–628), and by the
Plague of Justinian, which crippled both states. Arab tribes had served as mercenaries for both empires in decades prior to the invasion and that experience gave them valuable military tactical skills and familiarity with the battlefields they would fight on against the two empires.
Conquest of the Sasanian Empire 's conquest of
IraqThe first military move following the suppression of rebellions in Arabia was the invasion of the Sasanian Empire. In 633 Caliph Abu Bakr sent troops out to Sasanian-controlled Iraq, i.e. southern modern-day Iraq. Abu Bakr sent his general, Khalid ibn al-Walid, to conquer
Mesopotamia after the
Ridda wars. After entering Iraq with his army of 18,000, Khalid won decisive victories in four consecutive battles: the
Battle of Chains, fought in April 633; the
Battle of River, fought in the third week of April 633; the
Battle of Walaja, By now, almost the whole of Iraq was under Islamic control. Khalid received a call for help from
Dumat al-Jandal in Northern Arabia, where another Muslim general,
Iyad ibn Ghanm, was trapped among the rebel tribes. Khalid diverted there and defeated the rebels in the
Battle of Dawmat al-Jandal in the last week of August 633. Returning from Arabia, he received news that a large Persian army was assembling. Within a few weeks, he decided to defeat them piecemeal in order to avoid the risk of defeat by a large unified Persian army. Four divisions of Persian and
Christian Arab auxiliaries were present at Hanafiz, Zumiel, Sanni, and Muzieh. In November 633, Khalid divided his army into three units and attacked these auxiliaries one by one from three different sides at night, starting with the
Battle of Muzayyah, then the
Battle of Saniyy, and finally the
Battle of Zumail. These devastating defeats ended Persian control over Iraq. In December 633, Khalid reached the border city of Firaz, where he defeated the combined forces of the
Sasanian Persians,
Byzantines and Christian Arabs in the
Battle of Firaz. This was the last battle in his conquest of Iraq. Khalid then left Mesopotamia to lead another campaign in Syria against the Byzantine Empire, after which Mithna ibn Haris took command in Mesopotamia. The Persians once again concentrated armies to regain Mesopotamia, while Mithna ibn Haris withdrew from central Iraq to the region near the
Arabian desert to delay war until reinforcement came from Medina. Umar sent reinforcements under the command of
Abu Ubayd al-Thaqafi. This army suffered a severe defeat from the Sasanian army in 634 at the
Battle of the Bridge in which Abu Ubayd was killed, and Al-Muthanna saved the army from complete disaster by heroically defending a bridge over the Euphrates. The response was delayed until after a decisive Muslim victory against the Romans in the
Levant at the
Battle of Yarmouk in 636. Umar was then able to transfer forces to the east and resume the offensive against the Sasanians. Umar dispatched 36,000 men along with 7500 troops from the Syrian front, under the command of
Sa'd ibn Abi Waqqas against the Persian army. The
Battle of al-Qadisiyyah, the decisive battle of the campaign (near modern Najaf) followed, with the Persians prevailing at first, but, on the third day of fighting, the Muslims gained the upper hand. The legendary Persian general
Rostam Farrokhzad was killed during the battle. According to some sources, the Persian losses were 20,000, and the Arabs lost 10,500 men. Following this battle, the Arab Muslim armies pushed forward toward the Persian capital of
Ctesiphon (also called Madā'in in Arabic), which was quickly evacuated by
Yazdegerd III after a
brief siege. After seizing the city, they continued their drive eastwards, following Yazdgird and his remaining troops as they attempted to regroup in the Zagros mountains. Within a short span of time, the Arab armies defeated a major Sasanian counterattack in the
Battle of Jalula, as well as other engagements at
Qasr-e Shirin, and Masabadhan. By the mid-7th century, the Arabs controlled all of Mesopotamia, including the area that is now the Iranian province of
Khuzestan. It is said that Caliph Umar did not wish to send his troops through the
Zagros Mountains and onto the Iranian plateau. One tradition has it that he wished for a "wall of fire" to keep the Arabs and Persians apart. Later commentators explain this as a common-sense precaution against over-extension of his forces. The Arabs had only recently conquered large territories that still had to be garrisoned and administered. The continued existence of the Persian government was, however, incitement to revolt in the conquered territories and unlike the Byzantine army, the Sasanian army was continuously striving to regain their lost territories. Finally, Umar pressed forward, which eventually resulted in the wholesale conquest of the Sasanian Empire. Yazdegerd, the Sasanian king, made yet another effort to regroup and defeat the invaders. By 641, he had raised a new force, which made a stand at the
Battle of Nahavand, some forty miles south of
Hamadan in modern Iran. The Rashidun army, under the command of Umar's appointed general
Al-Nu'man ibn Muqrin, attacked and again defeated the Persian forces. The Muslims proclaimed it the Victory of Victories (Fath al-futuh), after which the Persians were unable to offer any effective resistance. Though Yazdegerd was unable to raise another army, the invading Arabs advanced slowly because "distances were great, the population hostile, and towns and fortresses had to be captured one by one". Yazdegerd retreating east with a dwindling band of supporters, eventually to Khurasan where he was assassinated. In 642 Umar sent the army to conquer the remainder of the
Persian Empire. The entirety of present-day Iran was conquered, followed by
Greater Khorasan (which included the modern Iranian Khorasan province and modern Afghanistan),
Transoxania,
Balochistan and
Makran (part of modern-day Pakistan), Azerbaijan,
Dagestan, Armenia and Georgia; these regions were later re-conquered during Uthman's reign with further expansion into the regions which were not conquered during Umar's reign; hence, the Rashidun Caliphate's frontiers in the east extended to the lower
Indus River and north to the
Oxus River.
Wars against the Byzantine Empire Unlike the Sasanian
Persians, the Byzantines after losing Syria, retreated back to Anatolia which was heavily fortified. As a result, they also lost Egypt to the invading Rashidun army, although the civil wars among the Muslims halted the war of conquest for many years, and this gave time for the
Byzantine Empire to recover.
Conquest of Byzantine Syria 's invasion of
Syria After
Khalid ibn al-Walid consolidated his control of Iraq, Abu Bakr sent four armies to Syria on the Byzantine front under four different commanders:
Abu Ubayda ibn al-Jarrah (acting as their supreme commander),
Amr ibn al-As,
Yazid ibn Abi Sufyan and
Shurahbil ibn Hasana. However, their advance was halted by a concentration of the Byzantine army at Ajnadayn. Abu Ubayda then sent for reinforcements. Abu Bakr ordered Khalid, who by now was planning to attack
Ctesiphon, to march from Iraq to Syria with half his army. There were 2 major routes to Syria from Iraq, one passing through
Mesopotamia and the other through Dumat al-Jandal. Khalid took an unconventional route through the
Syrian Desert, and after a perilous march of 5 days, appeared in north-western Syria. The border forts of
Sawa,
Arak,
Tadmur,
Sukhnah,
al-Qaryatayn and
Hawarin were the first to fall to the invading Muslims. Khalid marched on to
Bosra via the
Damascus road. At Bosra, the corps of Abu Ubayda and Shurahbil joined Khalid, upon which, per Abu Bakr's orders, Khalid assumed overall command from Abu Ubayda. Bosra, caught unprepared, surrendered after a brief siege in July 634 (
see Battle of Bosra), effectively ending the dynasty of the
Ghassanids. From Bosra, Khalid sent orders to the other corps commanders to join him at Ajnadayn, where, according to early Muslim historians, a Byzantine army of 90,000 (modern sources state 9,000) was concentrated to push back the Muslims. The Byzantine army was defeated decisively on 30 July 634 in the
Battle of Ajnadayn. It was the first major
pitched battle between the Muslims and Byzantines and cleared the way for the former to capture central Syria.
Damascus, the Byzantine stronghold, was conquered shortly after on 19 September 634. The Byzantine army was given a deadline of 3 days to flee as far as they could, with their families and treasure, or simply agree to stay in Damascus and pay tribute. After the three days had passed, the Muslim cavalry, under Khalid's command, attacked the Roman army by catching up to them using an unknown shortcut at the
Battle of Marj al-Dibaj. On 22 August 634, Abu Bakr died, making Umar his successor. Umar replaced Khalid with
Abu Ubayda ibn al-Jarrah as overall commander of the Muslim armies, though Khalid continuing play an important part in the conquests under Abu Ubayda. The conquest of Syria slowed down under Abu Ubayda while he relied heavily on the advice of Khalid, who he kept close at hand. The last large garrison of the Byzantine army was at Fahl, which was joined by survivors of Ajnadayn. With this threat at their rear, the Muslim armies could not move further north nor south. Thus Abu Ubayda decided to deal with the situation and defeated and routed this garrison at the
Battle of Fahl on 23 January 635, which proved to be the "Key to Palestine". After this battle Abu Ubayda and Khalid marched north towards
Emesa; Yazid was stationed in Damascus while Amr and Shurahbil marched south to capture Palestine. The prisoners taken in the battle informed them about Emperor Heraclius's plans to take back Syria. They said that an army possibly 200,000 strong would soon emerge to recapture the province. Khalid stopped here on June 636. As soon as Abu Ubayda heard the news of the advancing Byzantine army, he gathered all his officers to plan their next move. Khalid suggested that they should consolidate all of their forces present in the province of Syria (Syria, Jordan, Palestine) and then move towards the plain of Yarmouk for battle. Abu Ubayda ordered the Muslim commanders to withdraw from all the conquered areas, return the tributes they had previously gathered, and move towards Yarmouk. Heraclius's army also moved towards Yarmouk, but the Muslim armies reached it in early July 636, a week or two before the Byzantines. Khalid's
mobile guard defeated the Christian Arab auxiliaries of the Roman army in a
skirmish. In the third week of August, the
Battle of the Yarmuk was fought, resulting in the whole of Syria falling into Muslim hands. The battle lasted 6 days during which Abu Ubayda transferred the command of the entire army to Khalid. Outnumbered five-to-one, the Muslims nevertheless defeated the Byzantine army in October 636. Abu Ubayda held a meeting with his high command officers, including Khalid, to decide on future conquests, settling on
Jerusalem. The siege of Jerusalem led to great hunger but it negotiated a treaty of surrender with Umar with very generous terms. Christians were promised protection, freedom of worship, that churches would not be turned into mosques, and a tax less heavy than what they had paid Byzantium.
Jerusalem surrendered in April 637 and Caliph Umar's appearance wearing a coarse robe made a strong impression on Jerusalemites accustomed to Byzantine splendor. He allowed the
Church of the Holy Sepulchre to remain and prayed on a prayer rug outside of the church. Abu Ubayda sent Amr ibn al-As, Yazid ibn Abi Sufyan, and Shurahbil ibn Hasana back to their areas to reconquer them; most submitted without a fight. Abu Ubayda himself, along with Khalid, moved to northern Syria to reconquer it with a 17,000-man army. Khalid, along with his cavalry, was sent to Hazir and Abu Ubayda moved to the city of Qinnasrin. Khalid defeated a strong Byzantine army at the
Battle of Hazir and reached Qinnasrin before Abu Ubayda. The city surrendered to Khalid, and soon after, Abu Ubayda arrived in June 637. Abu Ubayda then moved against
Aleppo, with Khalid commanding the cavalry as usual. After the
Battle of Aleppo the city finally agreed to surrender in October 637.
Occupation of Anatolia and
Armenia In the mountains of Asia Minor, the Muslims enjoyed less success, with the Byzantines adopting the tactic of "guerilla warfare", refusing to give battle to the Muslims, while the people retreated into castles and fortified towns when the Muslims invaded; instead, Byzantine forces ambushed Muslim raiders as they returned to Syria carrying plunder and slaves. Abu Ubayda and Khalid ibn al-Walid, after conquering all of northern Syria, moved north towards
Anatolia taking the fort of
Azaz to clear the flank and rear of Byzantine troops. On their way to Antioch, a Roman army blocked them near a river on which there was an iron bridge. Because of this, the following battle is known as the
Battle of the Iron Bridge. The Muslim army defeated the Byzantines and
Antioch surrendered on 30 October 637 AD. Later during the year, Abu Ubayda sent Khalid and Iyad ibn Ghanm at the head of two separate armies against the western part of
Jazira, most of which was conquered without strong resistance, including parts of Anatolia,
Edessa and the area up to the
Ararat Plain. Other columns were sent to Anatolia as far west as the
Taurus Mountains, the important city of
Marash, and
Malatya, which were all conquered by Khalid in the autumn of 638. During Uthman's reign, the Byzantines recaptured many
forts in the region and on Uthman's orders, a series of campaigns were launched to regain control of them. In 647, the governor of Syria
Mu'awiya ibn Abi Sufyan launched an expedition into Anatolia, invading
Cappadocia and attacking
Caesarea Mazaca. In 648 the Rashidun army raided
Phrygia. A major offensive into
Cilicia and
Isauria in 650–651 forced the Byzantine Emperor
Constans II to enter into negotiations with Mu'awiya. The truce that followed allowed a short respite and made it possible for Constans II to hold on to the western portions of Armenia. In 654–655, on the orders of Uthman, an expedition prepared to attack
Constantinople, but this plan was not carried out due to the civil war that broke out in 656. The Muslim advance north was stopped by the barrier of the
Nur Mountains. The Taurus Mountains in Turkey marked the western frontiers of the Rashidun Caliphate in Anatolia during Caliph Uthman's reign. In the frontier area where
Anatolia met Syria, the Byzantine state evacuated the entire population and laid waste to the countryside, creating a
no man's land where any invading army would find no food. For decades afterwards, a guerrilla war was waged by Christians in the hilly countryside of north-western Syria supported by the Byzantines. At the same time, the Byzantines began a policy of launching raids via sea on the coast of the caliphate with the aim of forcing the Muslims to keep at least some of their forces to defend their coastlines, thus limiting the number of troops available for an invasion of Anatolia. Possessing some of the most productive and fertile farmland in the entire world, the Nile Delta made Egypt the "granary" of the Byzantine empire. Control of it meant that the caliphate could weather droughts without the fear of famine. In 639, Egypt was a prefecture of the Byzantine Empire but had been occupied just a decade before by the Sasanian Empire under
Khosrau II (616 to 629). The power of the Byzantine Empire was shattered during the Muslim conquest of Syria, and therefore the conquest of Egypt was much easier. The Muslim general
Amr ibn al-As began the conquest of the province on his own initiative in 639. The majority of the Byzantine forces in Egypt were locally raised
Coptic forces, intended to serve more as a police force; since the vast majority of Egyptians lived in the Nile River valley, surrounded on both the eastern and western sides by desert, Egypt was felt to be a relatively secure province. In December 639, Amr entered the Sinai with a large force and took
Pelusium, on the edge of the Nile River valley, and then defeated a Byzantine counter-attack at
Bilbeis. in Egypt today, the Roman/Byzantine fortress that occupied the site of what is now
Old Cairo Contrary to expectations, the Arabs did not head for
Alexandria, the capital of Egypt, but instead for a major fortress known as
Babylon located at what is now Cairo. They advanced rapidly into the
Nile Delta. The imperial garrisons retreated into the walled towns, where they successfully held out for a year or more. Amr was planning to divide the Nile River valley in two. The Arab forces won a major victory at the
Battle of Heliopolis in 640, cleverly luring Byzantine forces away from the Babylon Fortress. However, Amr found it difficult to advance further because major cities in the
Nile Delta were protected by water and because Amr lacked the
machinery to break down city fortifications. Amr next proceeded towards
Alexandria, which was surrendered to him by a treaty signed on 8 November 641. The
Thebaid seems to have surrendered with scarcely any opposition. The ease with which this valuable province was wrenched from the Byzantine Empire is said to have been due to the treachery of
Cyrus, prefect of Egypt and
Patriarch of Alexandria, and the incompetence of the Byzantine generals, as well as the loss of most of the Byzantine troops in Syria. Cyrus had persecuted the local
Coptic Christians. He was one of the advocates of
monothelitism, a 7th-century Christian heresy, and some have accused him of having been a secret convert to Islam. In 645, during Uthman's reign, the Byzantines briefly regained Alexandria, but it was retaken by Amr in 646. In 654 an invasion fleet sent by
Constans II was repulsed. After this, no serious effort was made by the Byzantines to regain possession of the country. The Muslims were assisted by some Copts, who found the Muslims more tolerant than the Byzantines, and of these, some turned to Islam. In return for a tribute of money and food for the occupation troops, the Christian inhabitants of Egypt were excused from military service and left free in the observance of their religion and the administration of their affairs. Others sided with the Byzantines, hoping that they would provide a defense against the Arab invaders.
Conquest of the Maghreb (Sufetula), present-day Tunisia After the withdrawal of the Byzantines from Egypt, the
Exarchate of Africa (i.e. that part of Byzantine North Africa west of Egypt), under its exarch (governor),
Gregory the Patrician declared its independence.
Abd Allah ibn Sa'd sent raiding parties to the west, resulting in considerable plunder and encouraging him to propose a campaign to conquer the Exarchate, which Uthman approved. A force of 10,000 soldiers was sent as reinforcement. The Rashidun army assembled in
Cyrenaica, and from there marched west, first capturing
Tripoli, and then
Sufetula, Gregory's capital. In the
ensuing battle in 647, the Exarchate was defeated and Gregory was killed due to the superior tactics of
Abd Allah ibn al-Zubayr. Afterward, the people of
North Africa sued for peace, agreeing to pay an annual tribute. Instead of annexing
North Africa, the Muslims preferred to make North Africa a
vassal state, fearing a counter offensive. When the stipulated amount of the tribute was paid, the Muslim forces withdrew to Barqa. Following the
First Fitna, the first Muslim civil war, Muslim forces withdrew from North Africa to Egypt. The
Umayyad Caliphate would later re-invade North Africa in 664.
Campaign against Nubia (Sudan) A campaign was undertaken against
Nubia during the Caliphate of Umar in 642, but failed after the
Makurians won the
First Battle of Dongola. The Muslim army pulled out of Nubia with nothing to show for it. Ten years later, Uthman's governor of Egypt, Abdullah ibn Saad, sent another army to Nubia. This army penetrated deeper into Nubia and laid siege to the Nubian capital of
Dongola. The Muslims damaged the
cathedral in the center of the city, but Makuria also won this
battle. As the Muslims were unable to overpower Makuria, they
negotiated a mutual non-aggression treaty with their king,
Qalidurut. Each side also agreed to afford free passage to each other through their respective territories. Nubia agreed to provide 360 slaves to Egypt every year, while Egypt agreed to supply grain, horses, and textiles to Nubia according to demand.
Conquest of the islands of the Mediterranean Sea During Caliph Umar's reign, the governor of Syria,
Mu'awiya ibn Abi Sufyan, sent a request to build a naval force to invade the islands of the
Mediterranean Sea but the proposal was rejected by Umar who believed that the risk to the soldiers was too great. Once Uthman became caliph however, he approved Mu'awiya's request. In 650, Mu'awiya attacked
Cyprus, conquering the capital,
Constantia, after a brief siege, but signed a treaty with the local rulers. During this expedition, a relative of Muhammad, Umm Haram, fell from her mule near the
Salt Lake at
Larnaca and was killed. She was buried in that same spot, which became a holy site for many local Muslims and Christians and in 1816, the
Hala Sultan Tekke was built there by the
Ottomans. After apprehending a breach of the treaty, the Arabs re-invaded the island in 654 with five hundred ships. This time, however, a garrison of 12,000 men was left in Cyprus, bringing the island under Muslim influence. After leaving Cyprus, the Muslim fleet headed towards
Crete and then
Rhodes and conquered them without much resistance. From 652 to 654, the Muslims launched a naval campaign against
Sicily and captured a large part of the island. Soon after this, Uthman was murdered, ending his expansionist policy, and the Muslims accordingly retreated from Sicily. In 655 Byzantine Emperor
Constans II led a fleet in person to attack the Muslims at
Phoinike (off
Lycia) but it was defeated: both sides suffered heavy losses in the
battle, and the emperor himself narrowly avoided death.
Rashidun military The Rashidun military was the primary arm of the Islamic armed forces of the 7th century, serving alongside the
Rashidun navy. The army maintained a very high level of discipline, strategic prowess, and organization, along with the motivation and initiative of the officer corps. For much of its history, this army was one of the most powerful and effective military forces throughout the region. At the height of the Rashidun Caliphate, the maximum size of the army was around 100,000 troops.
Rashidun army and
lamellar leather armour. His sword is hung from a
baldric, and he carries a leather shield. The Rashidun army was divided into
infantry and
light cavalry. Reconstructing the military equipment of early Muslim armies is problematic. Compared with Roman armies or later medieval Muslim armies, the range of visual representation is very small, often imprecise. Physically, very little material evidence has survived, and much of it is difficult to date. The soldiers wore iron and bronze segmented helmets from Iraq, of Central Asian type. The standard form of body armor was
chainmail. There are also references to the practice of wearing two coats of mail (''dir'ayn''), the one under the main one being shorter or even made of fabric or leather.
Hauberks and large wooden or
wickerwork shields were also used as protection in combat. Umar was the first Muslim ruler to organize the army as a state department, in 637. A beginning was made with the Quraysh and the
Ansar and the system was gradually extended to the whole of Arabia and to Muslims of conquered lands. The basic strategy of early Muslim armies on the campaign was to exploit every possible weakness of the enemy. Their key strength was mobility. The cavalry had both horses and camels, the latter used as both transport and food for long marches through the desert (
e.g., Khalid ibn al-Walid's extraordinary march from the Persian border to Damascus). The cavalry was the army's main strike force and also served as a strategic mobile reserve. The common tactic was to use the infantry and archers to engage and maintain contact with the enemy while the cavalry was held back till the enemy was fully engaged. Once fully engaged, the enemy reserves were held by the infantry and archers, while the cavalry executed a pincer movement (like modern tank and mechanized divisions) to attack the enemy from the sides or to assault their base camps. The Rashidun army was, in quality and strength, below the standard set by the Sasanian and Byzantine armies. Khalid ibn al-Walid was the first general of the Rashidun Caliphate to successfully conquer foreign lands. During his campaign against the Sasanian Empire (Iraq, 633–634) and the Byzantine Empire (Syria, 634–638), Khalid developed brilliant tactics that he used effectively against both enemy armies. Abu Bakr's strategy was to give his generals their mission, the geographical area in which that mission would be carried out, and resources for that purpose. He would then leave it to his generals to accomplish their missions in whatever manner they chose. In contrast, Caliph Umar, in the latter part of his Caliphate, adopted a more hands-on approach, directing his generals where to stay and when to move to the next target and who was to command the left and right wing of the army in each particular battle. This made conquests comparatively slower but made the campaigns well-organized. Uthman on the other hand reverted to Abu Bakr's method, giving missions to his generals and leaving the details to them.
Rashidun banners and standards The Rashidun Caliphate utilized a dual system of military banners inherited from the prophetic era. According to tradition, the Prophet's flag (
raya) was black, while his standard (
liwa) was white. • '
The Black Standard (al-rāyat as-sawdāʾ):' Also known as the "Banner of the Eagle" (
al-ʿuqāb)., it served as the primary military identification for the caliphate's armies. This banner gained significant eschatological weight in later Islamic history, though it was standard military equipment during the conquests. • '
The White Banner (al-liwa al-abyad):' This signified supreme military command and was often carried by the Caliph or the commander-in-chief of a campaign. At the
Battle of Siffin, the Rashidun caliph
Ali reportedly used the white
liwa of the Prophet. In addition to these central banners, tribal contingents carried their own distinct flags (
rayat). During the caliphate of
Umar, there was a concerted effort to centralize authority by assigning these tribal banners to veterans with "Islamic priority" (
ahl al-sabiqa). Historically, these tribal banners varied in color; for example, the
Kinda carried black, while the Ash'arīyün carried white with a black border.
Rashidun navy The early caliphal navy managed to mark the beginning of a long time legacy of Islamic maritime enterprises from the
Conquest of Cyprus, the famous
Battle of the Masts up to the exploits of their successor states such as in the area located in between the Jihun River (Oxus/Amu Darya) and the Syr Darya in Transoxiana, to Sindh (present day Pakistan) by the
Umayyad Caliphate, the naval core of privateers stationed at
La Garde-Freinet by the
Umayyad state of Córdoba, and the
conquest of Sicily by the
Aghlabid dynasty. ==Governance==