If you intend to go to college for one year and then apply into one of the service academies, why declare a major at all? Service academies don’t take transfer students in the traditional sense: they don’t care if you’ve attended college for a year, but you still have to enter as a plebe and attend for four years. Most colleges don’t require you to declare a major until your sophomore year, so if you intend to stay for just one year you don’t have to declare a major at all. Just take some classes that make sense.
If you intend to major in engineering or physics, there are prerequisite classes you will need to take in your first year of college if you want to stay on track to graduate in four years. You might as well get a jump on those and start with a program of calculus I, general physics I, and intro computer science. But service academies also require and cultivate the humanities and social sciences:
To prepare yourself for the academic curriculum at West Point, you should complete four years of English with a strong emphasis on composition, grammar, literature and speech…two years of a foreign language…and one year of U.S. history, including courses in geography, government and economics.
So you can also take an introductory English composition class and start a foreign language (picking a critical language, like Arabic or Mandarin Chinese, would be a good move).
Just take the bare minimum to stay full-time if you need to be full-time to do ROTC - that’s usually 12 hours, which is usually 3-4 courses a semester. So do like calculus I, physics I, English comp and language 101 your first semester, then cal II, an intro CS class, language 102 and some easy English literature course your second semester. Or something like that. Then spend the rest of your time concentrating on fitness and ROTC, maybe play an intramural sport.