From various USNA sources, this is the Midshipman Oath of Office:
I will support and defend the Constitution of the United States against all enemies, foreign and domestic; that I will bear true faith and allegiance to the same; that I take this obligation freely, without any mental reservation or purpose of evasion; and that I will well and faithfully discharge the duties of the office on which I am about to enter. So help me God.
Which, incidentally, is the same oath you will take upon graduation, and upon each promotion thereafter.
So learn it well.