We present a rare case of four-vessel aortic arch with an aneurysmal aberrant right retro-esophageal subclavian artery (ARSA) in a healthy, asymptomatic active duty U.S. military male. ARSA has a prevalence of 0.6%-1.4%, of which ∼80%-84% are retro-esophageal ARSAs. Intrathoracic subclavian artery aneurysms are rare and often occur in association with congenital aortic arch anomalies and/or concomitant thoracic aortic pathology. This case adds to three previously documented cases of thoracic aortic disease (TAD) in the U.S. military and is the second documented case of ARSA in the U.S. military. This case highlights successful TAD identification in a service member before clinical decompensation.