Did you understand it?

I, John Doe, having been appointed an officer in the Army of the United States, as indicated above in the grade of Second Lieutenant do solemnly swear  that I will support and defend the Constitution of the United States against all enemies, foreign or domestic, that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservations or purpose of evasion; and that I will well and faithfully discharge the duties of the office upon which I am about to enter; So help me God.