The ill-equipped and untrained Arab armies had fought on two fronts at the same time during the early regime of the second Caliph. On the front of Iraq, they engaged the large armies of Chosroes, the mighty Persian Emperor and on the Syrian front they were arrayed against the formidable forces of the Byzantine Emperor.  
    The Arabs fought a battle all day long against the formidable Roman forces in Syria. The issue hung in balance. The Arab warriors assembled in their camp to review their day's progress. At last a gallant soldier stood up and addressed them in a resolute voice:  
    
    "Brothers! God is with us. We are fighting for the noble cause of establishing a regime based on equality, fraternity and justice. Tomorrow I want to teach a lesson to these Roman hordes."  
    "What?" enquired a voice.  
    "I propose to face the sixty thousand sturdy soldiers of Jabla, leader of Ghassans, with 30 Muslims only."  
    "Are you serious, Abu Sulaiman?" enquired the aged Abu Sufyan.  
    "Yes", replied Khalid bin Waleed whose nickname was Abu Sulaiman.  
    " I think you have overestimated your strength. In this way you would be playing with the valuable lives of the Muslims", retorted Abu Sufyan.  
    "No, not at all. In reality, I want to save the valuable lives of the Muslims. In this way, I want to overawe the enemy who are proud of their superior strength and military equipment", replied Khalid bin Waleed.  
  
    At last Abu Ubaidah commander of the Arab forces, intervened and it was agreed that the lion-hearted Khalid bin Waleed would face the sixty thousand well equipped sturdy soldiers of Jablah bin Ghassan with sixty Muslims instead of thirty. The next day Khalid bin Waleed with 59 companions fought a memorable battle unparalleled in the history of military warfare against 60 thousand Christians. The battle raged all day long and the sixty Arabs were lost in a sea of armed men, and fought like lions against the surging waves of enemy forces bent upon sweeping them off their feet. The occasional cry of Allah-u-Akbar (God is Great) raised above the din of the battle proclaimed their existence to their fellow fighters who were watching the progress of the battle with great anxiety. At last, with one last effort Khalid bin Waleed who was fighting like a hero, won the day and the Christians were routed with heavy losses. The invincible Khalid won a memorable battle unheard of in the history of warfare. The victory established Arab's superiority over the Romans despite their exceptional inferiority in numbers and equipment.  
    Abu Sulaiman, Khalid bin Waleed Al-Qarshi belonged to the most respectable Quraysh clan. His father, Abdush Shams Al-Waleed bin Al-Mughaira, was considered among the wisest men of Quraysh and was known for his oratory and bravery throughout Arabia. Khalid who was hardly 17 years old at the birth of Islam, evinced keen interest in the science of warfare, including riding, lancing and archery, in which he soon earned a high reputation. His memorable charge in the battle of Uhud against the Muslims from the rear was repulsed after hard fighting. Khalid bin Waleed accepted Islam in the 8th A.H. along with Amr bin Aas, another well-known figure in early Islam. His first appearance as a soldier of Islam was in the battle of Mauta, fought in the 8th A.H. in which he exhibited exceptional bravery and military skill. The Muslims, with barely 300 men faced a Roman army of 150 thousand well trained soldiers. The earlier Muslim commanders were killed fighting in the battle-field when the command of the Muslims was entrusted to Khalid bin Waleed, who fought like a lion and broke eight swords in a single battle. Taking a tough rear guard action, Khalid bin Waleed exhibited a rare military skill and got his men safely out of the thick of the battle.  
    The breach of agreement by the Quraysh of Mecca led to the invasion of the Holy city in which Khalid was entrusted with the command of the right flank of the Muslim army. The Muslims entered the Holy city without any resistance and the insurgents were granted free pardon by the kind-hearted Prophet of Islam. `The people themselves (ie of Mecca), however, were treated with special magnanimity' writes Phillip K. Hitti, `Hardly a triumphal entry in ancient annals is comparable to this'. The other campaigns in which Khalid took active part during the lifetime of the Prophet are the battles of Hunain, Najran and the seize of Taif.  
    The death of the Prophet caused gloom over the Muslims. With the disappearance of central authority, the Arabian tribes rose in revolt against their new faith. Hazrat Abu Bakr who was elected as the First Caliph of Islam was adamant in his insistence on unconditional surrender by the seceders or war unto destruction. Khalid bin Waleed was the hero of these wars. `Within some six months of his generalship he had reduced the tribes of Central Arabia to submission' (Hitti). Before his death, the Prophet (sws) had assigned to Osama the command of a campaign against the Romans. Hazrat Abu Bakr, on his election as the Caliph, was advised by his most trusted lieutenants not to despatch the Muslim force outside the Capital which was threatened from all sides. But the pious Caliph declined to set aside the order of his deceased master and despatched the force under Usama which had a sobering effect on the recalcitrant Arab tribes and contributed immensely in establishing the dwindling military prestige of Islam.  
    Khalid bin Waleed, the Sword of God, as the Prophet (sws) once called him, was the hero of the successive campaigns against the seceding Arabian tribes. He played a leading role in the pacification of Arabia. Toleiha, Musailma, the impostor and Malik bin Nawera, were defeated one after the other after hard fighting. According to the early historians of Islam, the campaign against the forty thousand sturdy coilers, led by Musailima, was the hardest ever fought by the warriors of early Islam in which the extra ordinary bravery and military skill of Khalid won the day and Musailima was killed in an adjoining garden. This victory established once more the military superiority of Islam all over Arabia.  
    The neighboring Persian and Roman Empires, which hitherto, scoffed at and underrated the Arabian military strength, now saw a threat to their interests in the rising power of Islam. The pacification of Northern Arabia brought Muslims in conflict with the Persians who ruled over Arabian Iraq and were acknowledged as overlords by the Nomad Arabian tribes inhabiting the neighboring areas. The Persians instigated these tribes to rise against Islam. Such machinations on the part of the Persians against Islam, obliged the kind hearted virtuous Caliph, Abu Bakr, to despatch forces under the command of the invincible Khalid bin Waleed to Iraq on the 12th of Muharram 12 A.H. The first to oppose them was Hormuz, a tyrant hated by his Arab subjects who ruled over the Delta region. Khalid divided his troops in three portions, placing Muthanna in command of the advance column, Adi, son of Hatim over the second and himself bringing up the rear. He advanced strategically on Al Hafir, the frontier military post of the Persian Empire.  `Thereupon Hormuz challenged Khalid', writes Sir William Muir `to single combat and though he treacherously posted an ambuscade, was in the encounter slain. The Muslims then rushed forward and great slaughter put the enemy to flight, pursuing them to the bank of the Euphrates', ("The Caliphate --- Its Rise, Decline and Fall"). The battle was called `Zaat as-Salasil' (Mistress of the Chains) because a major portion of the Persian army was tied up with one another by chains to prevent their giving way.  
    In another campaign near the great Canal of Tigris in which a small flying column under the command of Al-Muthanna was in great peril, Khalid arrived just in time to relieve his lieutenant, defeated the reinforced Persian army with heavy losses, a large number of enemy soldiers being either killed or drowned.  
    The Persian Court was now alarmed at the unexpected victories of a handful of untrained and ill-equipped Muslims against their force, much superior in number and organization. The Persian Emperor raised a levy of the loyal Arab clans and hastily despatched a formidable force under the command of Bahman, a veteran Persian General. The two armies met at Al Walaja, near the confluence of the two rivers in April 633 A.C. Khalid who divided his arm into three portions, marched forward his advanced columns to meet the enemy while he kept two columns in reserve and surprised the exhausted enemy by an ambuscade placed in the rear. Thus the superior tactics and the great military skill of Khalid won the day for the Muslims against the much superior Persian forces.  
    A bitter feeling was aroused among the bedouin Christian tribes, who appealed to Ardashir, the Persian Emperor, to avenge their defeat. A large combined force comprising bedouins and Persians was hurriedly despatched under a tried Persian General Japan to meet the Muslim force at Ulles in May 633. A.C. Leaving a strong detachment at Al-Hafir, to guard his rear, Khalid hastily marched forward to meet enemy. The battle was fiercely contested and for a long time the issue hung in balance. At last, after a fierce charge by Khalid, the Persians gave way and fled, leaving behind seventy thousand dead on the battle-field. In a single combat, Khalid had a Persian warrior, who was reputed to be equal to one thousand warriors.  
    By this time, the Persians were thoroughly disillusioned and their spirit was broken. Nevertheless, the bedouin Christians insisted on expelling the invaders. Amghisiya, a prosperous town in the neighborhood of Al Hira, was surprised by Khalid. The Caliph when apprised of these victories of the Muslim armies, cried out `O, Ye Quraysh, verily your lion, the lion of Islam, hath leapt upon the lion of Persia, and spoiled him of his prey. Women shall no more bear a second Khalid'.  
    Khalid with a flying squadron hastened to the canal head to close the sluices to enable his grounded boats to ascend the canal. Al Hira was besieged by Muslims and capitulated shortly after. A treaty was signed with the residents of Hira in 633 A.C. which was later rectified by the Caliph of Islam. Hira was made the Headquarters of Islamic forces and from here Khalid started the consolidation of his gains. The beneficial reforms introduced by Khalid in consultation with the Caliph in favour of agriculturists and the common man inhabiting the conquered countries provided a striking contrast to the Persian feudalism hitherto prevailing in these regions. Hence, the Muslims were welcomed as benefactors replacing the tyrannical Persian overlords. For precautionary measures Muslim garrisons were quartered here and there and the troops were kept ready in movable columns.  
    The next to be besieged was the fortress of Anbar, situated on the Euphrates about eighty miles above Babylon. The deep fosse adjoining the fortress was crossed by casting the bodies of worn out slain camels and the city capitulated without much resistance. Ain at Taur, a green spot in the neighborhood of Anbar, was also captured by the Muslims.  
    Khalid had now reached Al Firad, a place on Syrian Iraqi borders, which was divided by a river. The Syrian frontiers were guarded by a strong Byzantine garrison, which being alarmed at the success of Khalid, made a common cause with Persians and bedouin Christians in order to defeat the Muslim invaders. A long and severe conflict ensued, in which Muslims were victorious and the enemy lost more than one lakh soldiers.  
    The victories of Islam over the Persians established the supremacy of Islamic arms and the invincibility of Khalid bin Waleed, the Sword of God. Khalid stayed in Iraq for about fourteen months and during this period he fought and won fifteen engagements against an enemy which was far superior in men and arms. The Arabs, who hitherto, considered themselves much inferior to the Persians in all walks of life and acknowledged them their overlords, now shed off their inferiority complex and regained their self-confidence. The lightening victories of Khalid in Iraq which paralyzed the vast and resourceful Persian Empire in such a short space of time, may rank among the most glorious campaigns in the annals of military warfare and have placed him amongst the greatest Generals of all times. He had devised several new tactics which were hitherto unknown to the world, including the charge by the reserve force. He also proved to be a good administrator who consolidated his gains, stationed military garrison at suitable places to secure the area, effected agrarian and other reforms advantageous to the common man which endeared the Muslims to the locals in contrast to their previous feudal Persian overlords. The Muslims with their democratic leanings were preferable to Persian bureaucrats.  
    After the defeat of the combined forces at Firad in January 634 A.C. the season for Hajj pilgrimage having drawn close, Khalid attempted to secretly perform Hajj. Sir William Muir in his well-known work "The Caliphate--Its Rise, Decline and Fall", writes: `The season for the Mecca pilgrimage being now at hand, Khalid formed the singular resolve of performing it incognito unknown even to his royal master. So, having recruited his army for ten days on the well fought field, he gave orders to march slowly and by easy stages back to Al Hira. Then he set out secretly with a small escort on the pious errand. Without a guide he traversed the devious desert route with marvellous sagacity and speed. Having accomplished the rites of pilgrimage, he retraced his steps from Mecca with the like despatch, and re-entered Al Hira in early spring, just as the rearguard was marching in. So well had he kept his secret, that the army thought he had been all the while at Al Firad, and now was journeying slowly back. Even Abu Bakr, who himself presided at the pilgrimage, was unaware of the presence of his great General'.  
    The attitude of the Byzantine armies on the frontiers bordering Syria was equally threatening since the time of the Prophet (sws). The Byzantine armies had made frequent incursions into the Arab territories bordering Syria and carried away their cattle and other belongings. Khalid who was stationed on the Syrian frontiers, met with some success against the Byzantine armies. Caliph Abu Bakr, having realized the great danger looming on the Syrian horizon, requested the Muslims to enroll themselves for active service on the Syrian front. More than a thousand Companions of the Prophet (sws), including one hundred who had participated in the battle of Badr volunteered themselves. The Caliph in person went up to the Plain of Jurf to bid farewell to each brigade bound for Syria and gave the following command, as quoted by Sir William Muir: `Men, I have ten orders to give you, which you must observe loyally: Deceive none and steal from none; betray none and mutilate none; kill no child, nor woman, nor aged man; neither bark nor burn the date palms; cut not down fruit trees nor destroy crops; flocks, cattle nor camels except for food. You will also meet with men living in cells; leave them alone in that to which they have devoted themselves .... Instructions of a more general character were given to the leader-to promise good government to the invaded people, and to keep his promise; not to stay much at a time, and always to be straightforward; to respect ambassadors, but not to detain them long lest they become spies; to preserve secrecy where necessary, to make the round of sentinels by night and by day; and never to be slack.'  
    Three divisions comprising five thousand soldiers each were despatched to the Syrian front under the command of Shurjil bin Hasana, Amr bin Aas, and Yazid bin Abu Sufyan. Abu Ubaidah the would-be Supreme Commander on the Syrian front, was also entrusted with the command of a separate Division. But the Byzantines had mustered a force in the neighborhood of Yermuk which was ten times stronger than that of the Muslims. This necessitated the transfer of Khalid bin Waleed to the Syrian front. The wise Caliph Abu Bakr ordered Khalid to hurry up to the Syrian front with half of his forces, leaving the second half in Iraq under the command of Al-Muthanna. According to historians Tabari, Muqaddasi and Ballazuri, the Caliph had appointed Khalid as Supreme Commander of the Muslim forces on the Syrian front. The lightning march of Khalid and his men through a trackless, waterless and impassable desert lying between Iraq and Syria, is one of the most daring feats ever recorded in living history. He crossed the desert in five days and the eminence on which he stood sill bears the name `Thanniyat ul Ukab' (the Pass of the Eagle).  
    The Muslim army in Syria was divided into four corps which were operating under the command of four Generals in different sectors. Abu Ubaidah was in command of the division of Hems, with Headquarters at Jabia, Amr ibn Aas was in command of the Damascus Division and Sharjil ibn Hasana was in command of the Division operating in Jordan. On the advice of Umar, the Caliph Abu Bakr ordered the concentration of the entire Muslim force at Jaulan near Yermuk in April 634 A.C. in order to meet an enemy whose resources, wealth and supply of fighting material were unlimited. The Romans, too, drew together all their corps, and the huge Roman army encamped in the semi-circular loop of Yermuk river protected on three sides by the river which they considered to be an ideal camping ground. The Muslim army arrived later and occupied the bottle-neck. The Romans realized their mistake but it was too late. The two armies watched each other for two months when Khalid arrived on the scene. He was entrusted with the Supreme Command of the Muslim forces. According to all authentic historical sources, including that of Tabari, the army of Heraclius numbered two lacs and forty thousand whilst the Muslims were only forty thousand. The Roman army was commanded by some of their famous generals and warriors, including Theodore the Sakkellarius, Bannes the American and Jarja (George). Khalid bin Waleed, realizing the superiority of the Romans in numbers and arms, resorted to his usual tactics and divided his army into thirty eight equal corps, each commanded by tried warriors. On August 30, 634 A.C. the Romans, inspired by the priests, came out from their camp to encounter the Arabs. A terrible carnage ensued and the Romans were defeated with fearful slaughter. According to Tabari, more than one hundred and twenty thousand Romans perished in the valley of Wakusa and were drowned in the river. With this memorable victory in the Battle of yermuk, the whole of Syria lay at the feet of the Muslims. In this memorable battle Khalid bin Waleed exhibited a super military skill, extraordinary chivalry and rare strategic moves. When the news of the disaster was conveyed to the Byzantine Emperor Heraclius at Antioch, he said, `Farewell Syria, my fair province. Thou art enemy's now'; and he quitted Antioch for Constantinople. Khalid declared `Syria sat as quiet as a camel'. But before the decision of the battle of Yermuk, the Caliph Abu Bakr died and was succeeded by Umar. Immediately after his election as Caliph, Umar issued orders for the deposition of Khalid from the Supreme Command. The letter delivered to Khalid in the heat of battle of Yermuk was kept a secret till the issue was decided. Khalid gladly bowed down to the orders of the Caliph and till his death fought as an ordinary soldier in the armies of Islam. He exhibited a sense of discipline scarcely shown by a General of his calibre. Disregarding all the humiliation which this order might have caused him, he continued to serve with unflagging zeal as a faithful solder of Islam in all the campaigns fought in Syria thereafter.  
    During the Caliphate of Umar, Muslim forces won brilliant victories in Syria, Iraq, Persia and Egypt and the Islamic banner was carried to the western extremities of Egypt in the West and to the shores of the Caspian in the North. The siege of Damascus lasted for more than two months and one night when the birth of a child of the Lord Bishop was being celebrated in the city, Khalid along with his associates scaled the walls and opened the Eastern gate. The cry of Allah-u-Akbar rent the air, and the feasters having understood the critical situation capitulated to Abu Ubaidah, the Muslim Commander guarding the Western gate. The two armies --- one led by Khalid claimed to have captured the city and the other commanded by Abu Ubaidah which had accepted capitulation of the city on certain terms, met in the heart of the city. At last, the terms of the capitulation accepted by Abu Ubaidah were held good for the entire city and it was ratified by Caliph Umar.  
    Khalik took part in several campaigns fought in Syria, including those of Hems and Kansarain. With the conquest of Kansarain, the last stronghold of the Byzantines in Syria, the rule of Byzantines in Syria came to an end and the Emperor Heraclius retired to Constantinople never to return. The exceptional valour exhibited by Khalid in the campaign of Kansarain obliged Umar to change his view about him. He acknowledged openly : `God may bless Abu Bakr. He had greater sense for the right type of men than myself'.  
    The respect shown by the Muslim conquerors towards the conquered races in Iraq and Syria was to a great extent, responsible for establishing a stable government and sound administration in these regions. Writing in "Caliphate ---Its Rise, Decline and Fall", Sir William Muir acknowledges: `Had the Muslims ill-treated the people of Syria or persecuted their religion, their position would have been desperate indeed; but their leniency towards the conquered and their justice and integrity presented a marked contrast to the tyranny and intolerance of the Romans.....the Syrian Christians enjoyed more civil and political liberty under their Arab invaders than they had done under the rule of Heraclius and they had no wish to return to their former state....The Muslims, when they withdrew, returned the taxes which they had collected, since they were no longer able to fulfil their part of the bargain in guaranteeing security of life and property. A nestorian Bishop writes about the year 15: The Talites (Arabs) to whom God had accorded in our days the dominion, have become our masters; but they do not combat the Christian religion; much rather they protect our faith, they respect our priests and our holymen, and make gifts to our churches and our convents'. Thus, Muslims in Syria ruled both over the body and the heart of their subjects in Syria and Iraq.  
    The reason behind the deposition of Khalid was not malice on the part of the great Caliph Umar. He was too great a person to be associated with such acts. As Sir William Muir puts it: `The Military Chief had to give place to the civil functionary; sword to pen; Khalid to Abu Ubaidah. There is no occasion to seek any ulterior motives which might have led Umar to replace Khalid by Abu Ubaidah. Least of all can personal dislike have influenced him. Umar was too great for that.' Umar tried to remove the misunderstanding created among the people about the deposition of Khalid bin Waleed. He sent a rescript to the various provinces announcing that he had not deposed Khalid because of any fault on his part, but because people had begun to repose greater trust in Khalid than in God.  
    According to the celebrated historians Tabari and Ibni Asakir, Khalid bin Waleed, the Sword of God, died in Hems in 21 A.H. (644 A.C.).  
    Thus passed way the hero of hundreds of battles with an unrealized wish for martyrdom on his dying lips. `Alas', he murmured, `I, who fought hundreds of battles and have innumerable battle scars on my body, could bot be blessed with martyrdom --- the greatest ambition of all true Muslims'. On hearing the news of his death, Caliph Umar exclaimed, `The death of Khalid has created a void in Islam which cannot be filled.'  
    `The military campaigns of Khalid bin Waleed and Amr ibn al Aas' writes Philip K. Hitti, in his monumental work. "The History of the Arabs" which ensued in Iraq, Persia, Syria and Egypt are among the most brilliantly executed in the history of warfare and bear favourable comparison with those of Napoleon, Hannibal or Alexander'.