On this day in history, vastly outnumbered Muslim army outwitted the Byzantine!

Indeed, it is no exaggeration to state that the Battle of Yarmouk was one of the most decisive battles in history. In the course of six days, a vastly outnumbered Muslim army succeeded in annihilating a significantly larger Byzantine force. "How often has a small group overcome a mighty host by Allah's leave'' And Allah is with As-Sabirin (the patient). Allah (swt) says.

This victory permanently shifted the dominion in the Levant and Syria from the Byzantine Empire to the Caliphate. Moreover, this was the magnum opus of Khalid Ibn Al waleed (may Allah be pleased with him) , who has been immortalized in legends for his triumph.

It is recorded that Abdullah bin Abi Awfa said that during one battle, Allah’s Messenger waited until the sun declined, then stood among the people and said,

“O people! Do not wish to face the enemy (in a battle) and ask Allah to save you (from calamities). But if you should face the enemy, then be patient and let it be known to you that Jannah is under the shadows of the swords.”

He then stood and said,

“O Allah! Revealer of the (Holy) Book, Mover of the clouds, and Defeater of the Confederates, defeat them and grant us victory over them.”

The battle occurred over the course of six days. Though the Byzantines initially took the offensive and repulsed some Muslim counterattacks, they were unable to attack the main Muslims encampment. In addition, the Muslim army was able to use their foot and cavalry archers to great effect, placing them in prepared positions, and were thus able to halt the initial Byzantine advance.

Khalid arrayed infantry regiments in front of the Harir River, with three light cavalry divisions positioned behind the line, and one larger cavalry reserve under his personal command in the rear. Unlike the multiethnic Byzantine forces, the Muslims were united not only in their nationalist sentiment but also by a common faith. In both armies, infantry consisted of melee fighters and skirmishers (such as archers), and although the Muslims lacked heavy troops, which abounded in the ranks of their foes, they made up for this loss with higher mobility and unparalleled skill in hand-to-hand combat.

“O you who believe! When you meet (an enemy) force, take a firm stand against them and remember Allah much, so that you may be successful.” Allah (swt) says.

The decisive moment came when Khalid sent a cavalry detachment around the field to take over the only bridge on the Wadi Ruqqad, cutting off the only escape route of the imperial army. The fighting started on 20 August 636 CE with another duel, where Abu Ubaidah got the best of his foe, a Greek commanding officer named Gregory, and then the entire Muslim line charged.

As the infantry locked their kind on the opposing side in place, Khalid sprang into action and led a huge cavalry force, gathered from all of his cavalry divisions, around the Byzantine left flank. Vahan, realizing too late that he had been outwitted, failed to organize his disarrayed cavalry in time, and the Muslims smashed the Byzantine left into their center.

Surrounded on three fronts, the imperial troops began to rout, but unbeknownst to them, their escape had already been cut off. Imperial troops were massacred in their retreat, and many drowned in the river, while some fell to their deaths from steep hills of the valley. Khalid all but annihilated his foe and secured a crushing victory, whilst only taking around 4,000 casualties. Vahan either perished in the battle or, according to some, adopted a monastic lifestyle after the pulverizing defeat.

The skill of the Arab cavalry, particularly the horse archers, also gave the Muslim army a distinct advantage in terms of their ability to outmaneuver their Byzantine counterparts.

The battle also stimulated a change in military tactics and strategy on the part of the Byzantines. Having failed to defeat the Muslim armies in open battle.

Allah almighty says: “They will never fight against you all together except from fortified villages or from behind walls. Their courage is great among themselves; you think them to be united, yet their hearts are not united.”

Finally, the Muslim conquests, and the battle of Yarmouk in particular, destroyed the military reputation of Heraclius. Having failed to prevent the loss of half the empire, Heraclius retreated into isolation, by all accounts a broken man, a mere shadow of the former dynamic personality who had been victorious against the Persians merely a decade before.