[4] Islamic accounts state that Khalid ibn Walid reached the city of Bosra in June of 634 CE, after capturing several Syrian towns.

According to his instructions, Abu Ubaidah ibn al-Jarrah, who had already occupied the District of Hauran, which lay north-east of the river Yarmouk, was to remain at his position until Khalid arrived at Bosra.

Bosra, a large town and the capital of the Ghassanid Kingdom, contained a force of Byzantine and Christian Arabs, commanded by Roman officers.

This garrison consisted of 4,000 soldiers who all expected that more Islamic forces would soon arrive and that the Shurahbil detachment was only an advance guard, and remained within the walls of the fort.

Shurahbil and the Roman commander held talks with their forces drawn up for battle; the Muslims offered three choices: Islam, tribute, or the sword.

For the first few hours, the fighting continued at a steady pace, with neither side making any headway; but soon after midday, the superior strength of the Romans turned the battle in their favor.

The temper of Shurahbil's soldiers became suicidal as the real danger of their position became evident, and they fought with ferocity to avoid encirclement, which appeared to be the Roman's goal.

Khalid bin Walid wrote to Caliph Abu Bakr, informing him of the progress of his operations since his entry into Syria, and sent one-fifth of the spoils which had been won during the previous few weeks.

Hardly had Bosra surrendered when an agent sent by Shurahbil to the region of Ajnadayn returned to inform the Muslims that the concentration of Roman legions was proceeding apace.