Answer
Syria, a prominent Roman province, proved instrumental in the downfall of Emperor Macrinus. The province's legions, notably the Legio IV Scythica, played a pivotal role in backing Macrinus' rival, Elagabalus, whose grandmother, Julia Maesa, hailed from Syria. Their support added significant strength to Elagabalus' cause, eventually leading to Macrinus' defeat in the Battle of Antioch and his subsequent assassination.