▁many ▁days ▁before ▁his ▁arrival , ▁and ▁there ▁was ▁alarm ▁in ▁the ▁fort . ▁With ▁their ▁present ▁strength ▁they ▁could ▁hold ▁off ▁the ▁Muslim ▁force ▁under ▁I y ad , ▁but ▁they ▁would ▁not ▁have ▁a ▁chance ▁if ▁K hal id ' s ▁army ▁also ▁took ▁the ▁field ▁against ▁them . ▁In ▁des perate ▁has te ▁they ▁sent ▁cou riers ▁racing ▁to ▁neighbour ing ▁tribes . ▁The ▁Christian ▁Arab ▁tribes ▁respond ed ▁spir ited ly ▁to ▁the ▁appeal ▁for ▁help . ▁Cont ing ents ▁from ▁several ▁cl ans ▁of ▁the ▁Gh ass an ids ▁and ▁the ▁Kal b ▁joined ▁the ▁def enders ▁of ▁the ▁fort , ▁many ▁of ▁them ▁camp ing ▁under ▁the ▁fort ▁walls ▁because ▁of ▁the ▁ins u fficient ▁room ▁within ▁the ▁fort . ▁ ▁The ▁battle ▁ ▁K hal id ▁ibn ▁al - W al id ▁took ▁I y ad ▁under ▁command ▁and ▁incorpor ated ▁his ▁det achment ▁into ▁his ▁own ▁army . ▁He ▁deployed ▁I y ad ' s ▁men ▁on ▁the ▁south ▁of ▁the ▁fort ▁to ▁block ▁the ▁Arab ian ▁route ▁and ▁position ed ▁part ▁of ▁his ▁army ▁of ▁Ira q ▁to ▁the ▁east , ▁the ▁north ▁and ▁the ▁west ▁of ▁the ▁fort , ▁covering ▁the ▁routes ▁to ▁Ira q ▁and ▁Jordan ; ▁and ▁kept ▁the ▁remainder ▁back ▁as ▁a ▁strong ▁reserve . ▁K hal id ▁appreciated ▁that ▁at ▁present ▁the ▁fort ▁was ▁strongly ▁man ned ▁and ▁to ▁storm ▁it ▁in ▁its ▁present ▁state ▁would ▁prove ▁a ▁cost ly ▁operation . ▁He ▁therefore ▁decided ▁to ▁wait , ▁in