Sometimes yes, sometimes no.
They would occasionally have special envoys to do some real heavy diplomacy (Sarek on Journey to Babel, Ambassador Fox on “A taste of armageddon”).
Since you can’t always predict exactly when a diplomatic situation might arise, senior Starfleet officers were also given some basic training, I assume.
As I said in the other thread: it’s an idealized space navy. And sometimes foolish; they REALLY need Marines on board.
The 2D nature of Classic Trek battles never bothered me. It was just a limitation of the special effects of the time. By DS9, ships were consistently shown moving in 3 dimensions.
I always got the impression that while Star Fleet ferried diplomats around and had to do some diplomacy on the fly (especially during First Contacts etc), it was mainly the job of a different branch of the Federation. Especially in the old show where Diplomats were often the foil for Kirk.
Maybe Starfleet captains in the 23rd Century will have the power to solemnize marriages, but here on Earth they don’t.
Well, clearly the mission changed between TOS and TNG–in part, no doubt, to Spock’s influence in the Federation diplomatic corps in the decades in between. Picard clearly acted as a roving ambassador as much as a naval commander.
But in the canonical history of Star Trek, Starfleet didn’t evolve as a successor of the US military. The US government didn’t exist anymore due to the widespread social collapses of the 21st Century, the Eugenics Wars, and so on.
Yes, that’s right. I was trying to get at how we would get to something like Starfleet from our actual present-day reality. People were talking about how Starfleet is more like the Navy than the Air Force, which is undoubtedly true. But it seemed like some were extrapolating that to mean that it could evolve from the Navy, which I don’t entirely agree with.
My opinion is that a Starfleet-type of entity would either: evolve from an air-force with other elements added in later, or be created anew from a mix of the remnants of various entities. So I was really talking about our real future ‘history’ and trying (probably badly!) to highlight how it would differ from Star Trek’s canon history.
Another sci-fi example would be the Stargate SG-1 series. I think the space fleet that Earth eventually develops in that series evolved somewhat along the lines of my description. They started with the USAF and added in other military branches to form a joint-command. But then neither the Stargate-universe people, nor us real-universe people went through the Eugenics Wars in the mid-90s. . . 
Related thread, including ST references: RE: Are ships captains allowed to marry people at sea? - Cecil's Columns/Staff Reports - Straight Dope Message Board
I see that you are Suffering from a severe case of Americanitis.:rolleyes:The US might have identical officer ranks for it’s air force as for it’s army, but commonwealth countries do not, they have modified Navy ranks.
They do have Marines. Security officers do all the classical (meaning pre WW2) roles of Marines, which is shipboard security and being the core of away teams and boarding parties.
The Few. The Proud. The Redshirts.
Didja really need the rolleyes?
Yes, *Star Trek *has the conceit that the United States was the country that was more equal among equals in our future. The one world government that joined the United Federation of Planets still had a United States, and the Starfleet of the United Earth was headquartered in San Francisco.
Within a hundred years, we had the whole freaking galaxy speaking English with American accents. And using USA naval ranks.
Starfleet doesn’t use Commonwealth-style air force ranks, they use straight-up Navy ranks. There are admirals, not “space marshals” and “space chief marshals”; Kirk is a captain (not a group captain), there are commanders and lieutenant commanders but no wing commanders, and there are lieutenants and ensigns, but no flight lieutenants or flying officers or pilot officers.
A while back, I took part in a LARP that involved a steampunk setting in the old Republic of Texas. The steampunk elements involved adding airships to the standard military of the time. The premise was that airships were popular, so Texas was enthusiastic to incorporate them into their military and put them to use fighting Mexico. They formed an air corps, and put them under command of the Navy.
My point is that there are many options for what could happen from here, so we won’t necessarily end up with what that one TV show ends up with. It picked a format that made sense given the type of stories to be told and the audience expectations of the time, plus preferences of the originator. Reality is not constrained to Gene Roddenberry’s desires. 
And had Star Trek been created by someone from a Commonwealth country who’d served in a Commonwealth military, you’d have a point.
However Gene Roddenberry was an American who’d served in the American military and deliberately decided to use Navy ranks rather than Air Force ranks, which was the military branch he’d served in.
Let’s also remember the scene from the movie Star Trek Generations where Worf was promoted to Lt. Commander or Commander(I can’t remember which) which took place in the Holodeck in a simulation of a 19th Century Naval ship.
Or how about a little poetry?: Star Trek - "All I ask is a tall ship" - YouTube
In-story, Starfleet is not directly descended from any branch of any nation’s armed forces,
Out-of-story, it was a show created by an American writer, produced by an American studio, broadcast by an American network, starring a Canadian-born actor working in America, and initially broadcast to American audiences. Clearly the use of American Navy rank structure was meant to suggest a naval structure, not Commonwealth.
Can I leave a slightly off-topic bitch here about people who think “Yeoman” means a woman in a tiny skirt who does gopher work?
~VOW