This too I read over and over..military genius..incredible intelligence and innate understanding of psychological warfare and every terrain..
Khalid was the architect of most of the early Muslim military doctrines,
he was pioneer of almost every major tactic that Muslims used during Early Islamic conquest
. One of Khalid's major achievements in this context was utilizing the individual skills of Arab Bedouin warriors to a larger scale. He is believed to have developed them into an almost regular unit called Mubarizun
("champions"), who would issue personal challenges to the enemy officers. These were highly trained and skilled swordsmen, whom Khalid utilized effectively to slay as many enemy officers as possible, giving a psychological blow to enemy morale. The Battle of Ajnadayn
is perhaps the best example of this form of psychological warfare
. Moreover his biggest achievement was the conversion of Arab tactical doctrine into a strategic system.
Until Khalid, the Arabs were basically raiders and skirmishers. Khalid turned those skirmishing tactics into something that could be used anywhere. Thus he would skirmish the enemy to death: he would bring his army in front of his enemies and wait until the whole battle degenerated into a skirmishing affair between small units. Then, after exhausting the enemy units, he would launch his cavalry at their flanks employing Hammer and Anvil