Is it realistic for a Marine officer to make Lt. Colonel in twelve years?

That's impossible. Officer promotions are based on a time schedule and a peer group. There are only slight adjustments for people who are among the best. She probably would not be retained past 20 and retire as a Major.

The only ways I can think a Marine can make O-5 is in a battlefield promotion or if he is a surgeon of exceptional skill in a HIGHLY SPECIALIZED field, and even then, more than like not. I don't know about being charasmatic, or even charismatic. USMC has some of the strictest guidelines for time in service and promotion. Generally, 4 years as a LT, 8 years as a CPT, 4-5 years as a MAJ, and THEN, the LTC board. You are looking at 18 years on average, 15-16 if the guy walks on water and gets promoted TWICE, below the zone.

No, it's not realistic, especially if she has some black mark on her record, like a frat charge.

No promotion in the military is fully automatic for time, not even at the lowest levels. To make Pfc. in the Marine Corps you need not just 6 months' service but also to be recommended by your CO. It's a rubberstamp IF you don't have anything bad on your record.

Things are much more involved for officers than for enlisted personnel. The 18 months of service make but just one of several different requirements.

Now, am I right to assume you're talking about Sarah MacKenzie on the CBS show "JAG"? A lot of people assume that her character is the same age as the actress who played her, Catherine Bell. The problem with that is that we have to make several assumptions: if she graduated from high school, college, law school and OCS at the earliest possible normal times, by the time she joined JAG in 1997 she would just then be up for consideration for promotion to Captain (O-3). And that's assuming that the frat charge didn't completely scuttle her career. Also, we learn in season 10 that now-General Cresswell was the SJA in Okinawa who prosecuted her on the frat case.

I take it when she fraternized with her CO she was an officer. Unless she entered active duty with a direct commission to either first-lieutenant as a lawyer or a chaplain (the Corps uses Navy chaplains) or as a captain (0-3) in the Medical Corps (the Corps uses Navy doctors) it is IMPOSSIBLE. Under current promotional policies it takes 4 years TIS to move from newly appointed second-lieutenant to captain (0-3). The zone for promotion to major is between 10 and 10 1/2 years. A newly promoted major (0-4) should pin on his oak leaves in about 11 years, maybe 11 1/2 years. The zone for lieutenant-colonel is between 15 and 15 1/2 years. A newly promoted lieutenant-colonel should pin on his silver oak leaves at 16 years give or take. This is the optimum promotion time. I am retired Navy I entered with a class mate who selected the Marine Corps option. We entered active duty at the same time. We made 0-1, 0-2 and 0-3 on the same day since we went on active duty the same day. I made lieutenant-commander at 10 1/2 years he made major in 12 years. I made commander (0-5) in 15 years 3 months. He retired with 20 years as a major. Less than six-months after he retired I was promoted to captain with 20 years and 5 months. I good way to look at this is that a great Marine hero "Barney" Barnum (who I am proud to know) a Medal of Honor recipient, was promoted to colonel (0-6) in 23 years. I will promise you that even though I had what I consider an excellent career, I was no "Barney" Barnum. It is much harder to make field (0-4,5 and 6) or flag rank (0-7,8,9,10) than in any other service. I cannot even imagine how an officer in the Marine Corps could make lieutenant-colonel in less than 15 years. I think it is impossible.

In real life, the actress Catherine Bell was born in 1968. If she graduated from high school in 1986 and law school in 1994, that would mean that by 1997 she would have attained the rank of...

First Lieutenant (O-2). So no, it's not realistic for her character to be Lt. Colonel in the fourth season.

Probably not. It is possible, but would depend on whether any action was taken on the fraternization episode. the timing is about right, but the Corps takes a dim view of misbehaviour.

highly unlikely. 10 years is generally Major. officers are not promoted by their COs. they are promoted by the promotion board.

you will seldom find a ltcol that has been in for less than 14-15 years

No... more like 18 especially with fraternization on her record

Depends on what she started as, where she was, her combat record, among other things. a more realistic rank would be a Major or something like that.

yeah it took my grandpa 20 years to make colonel in the army. Which is known to promote much quicker than the Marines. its extremely unlikely trust me you would have to be idk but a very hoorah marine to do that