I left school in the middle of transferring from my junior college to a four year to join the Marine Corps in 2007. I had acceptance letters to multiple schools (UCSC,UCI,UCSD,UCSB) but I opted to do combat tours in Iraq and Afghanistan instead. As of right now, I feel like I've really screwed myself over in the long term, now that I'm out of the Marines and dying to jump back into school. Before I left, I had completed mostly general ed courses as well as completing general chem, Calc 2, and the first installment of physics for scientists and engineers. My questions for guidance are: Will I be able to "survive" the future engineering courses if I continue where I left off with a very fuzzy memory of the courses I did in the past? How heavily do the upper division courses rely on recalling detailed information from previous courses? Am i better off starting all over again from the beginning to make sure I get a strong grasp of the basics again (i.e. Calculus)? As of right now I'm going back to my Junior College for the fall and (If I choose) the schools I've applied for are willing to honor my old acceptance letters and accept me in the Spring. I originally applied to all these schools as a Bioengineering Major but as of right now I'm just not sure what I want to do in engineering anymore. I've been so out of focus in regards to school and so focused on being a good Marine that I'm so lost as this is all hitting me all at once. I want to combine my love of the ocean, marine biology, principle of engineering, and mechanics. All input is greatly appreciated.