In your opinion, have all branches of the military lost unit cohesiveness due to to political correctness being a focus?

I don't think the military has lost cohesiveness due to PC. Political Correctness, and many other things that are often "right" can hinder our ability to "make war." However that is what makes our nation stronger. We don't set our military outside of the law or separate from society. We are a fairly representative cross-section, and sometimes that has consequences.

Well,
1. Sweeping generalizations and absolutes are almost always incorrect, 'All Branches', in fact have lost cohesion due to an ambiguity.
What I mean is; are you suggesting that there is a loss of cohesion because.. there are now female Rangers? Or Taking action that is morally correct may violate some sort of order of non-interference? Are there other specific issues that you are thinking.. or maybe in general?

I honestly do not think that there has been any particular loss of cohesion due to changes of public policy or opinion. I'd refer you back to what 'public opinion' was to those veterans returning from Vietnam, or public policy about the VA.
I know some will be quick to point fingers... President Obama is the reason for the VA, when they have always been a problem, every administration. By Obama doing nothing really about the unnervingly high suicide rates among veterans, or about the backlogs and incompetency... is pretty much status quo.
We have all heard the lines, to 'do more with less'. Administrations that increase the Military Budget or spending, didn't go to us, improving quality of life for us, or dependents.. but increased to contractors to develop flying 'warplanes' that cannot defeat its 30 year old Attack and Fighter predecessors. Then again, I think we are all use to the endless face-palms over policy changes, sometime just so absurd you are convinced you are being pranked.

I do not think PC is the issue, its when we start to actually buy the political bullshit by the talking heads in offices. People said that it would hurt unit moral and cohesion to desegregate, or allow women into the military, that was often coming from sides that either never served, or started buying the bullshit they peddle. Lets face is, PC, talking about veteran suicides, the VA, STILL has nothing to do with vets, but make for great attack ads for candidates, and political platforms. This is nothing new.

Political Correctness likely has nothing to do with unit cohesiveness.

We want to blame all our woes on it, but we've been complaining about it for 20+ years, and the "Mothers of America" and the "Kinder Gentler Marine Corps" blah blah blah.

Political Correctness is society calling people out for being ignorant #%^#&holes. Some of it is over the top, granted, but the vast majority of it is people being unwilling to change, evolve, or understand that the world changes, and we as people need to adjust our attitudes accordingly.

Generally speaking, when people talk about PC, they talk about the "extremes" where as it is really the "moderate" side of not insulting people. That's all it means. It means not being a dick, because a group of people is different, or because you don't understand something.

Now, back to unit cohesiveness. Units are small communities and develop an Us v. Them mentality. PC by its nature tries to get rid of the "them" concept, so it's counter-philosophically, which I suppose someone can see as breaking up unit cohesiveness, but as it's focused on external forces, I find the premise lacking.