 Khalid utilized his better understanding of terrain in every possible way to gain strategic superiority over his enemies. During his Persian campaigns, he initially never entered deep into Persian territory and always kept the Arabian desert at his rear, allowing his forces to retreat there in case of a defeat. It was only after all the strong Persian and Persian-allied forces were routed that he penetrated deep into Euphrates region and captured the regional capital of Iraq, Al-Hira. Again, at Yarmouk, the terrain would help him in executing his grand strategy of annihilating the Byzantines.
